I tend to have insane micromanagement problems, so I tend to plan out every room I'll ever use and designate them the second my fort starts. Then I just cut off access to the stuff I don't need right away and dig it out as I need to.
I used to do that (de-designate "adjacent to open" digging designations), but now I use a burrow-modified version of it.
Make sure your miners are in a burrow (or each in one of a set of different burrows) which defines only
the current digging priority (although also food and drink and sleeping resources should be in it, really, unless you make that a second burrow that you turn off and on for them, as you adopt and reject your "slavedriver" persona).
I often start off with two miners and have one "Exploration" burrow that is designated to whichever stairwell(s) I currently want to delve into the depths with, while the second miner is in the burrow that (from all the pre-designated rooms) starts off covering something like the intended (and pre-designated) underground farming area, and then gets modified to cover other holes-that-need-to-be-dug as the need arises. Thus I'm gaining intelligence as to the caverns even as I'm making progress satisfying the initial space needs (first off, an underground hyper-general stockpile, to decamp the cart contents/components to, before the more complicated redistribution gets arranged).
This way I don't have to undesignate 'tricky' bits of mining, just because I don't want them to waste their time on the area just beyond, just yet, and can also safely make layer-upon-layer of channel/up-ramp designations, towards the eventual end of a cistern-like void[1], or deep moat. I can keep it all so that I can see it laid out at a glance, don't have to worry too much about northerly/westerly-bias of job designation on a macro scale (and can even micromanage room-digging to get the perimeter dug first, ready for the smoothers to attack the walls), and
can get the exploration guy retasked to help the void-maker or vice-versa, but still keep them on their own job (or each others', if I want to swap them!) without enforced physical separation of any kind.
The "vital parts" burrow, as it develops and is gradually added to, and shorn it of any inadvertent cavern-intruding segments, might also serve as an "everything inside and safe"-type burrow, should I ever need to assign the non-mining population to it for any tactical reason. (So far, I've never really used alerts of any kind, so this is a manual process, used purely on-demand, but it's an easy one in the early days of low population and by the time I'm up to hundreds of individuals I've usually got something more sophisticated in place.)
Really, it's easier to do than to describe. I've a feeling I've made a mess of the latter.
This may even help with OPs current issue, at least as an additional opportunity for quick-fixing the room situation. Find a block of solid stone (preferably of the material the King likes most... Assuming that isn't for some reason... you know, that type... And designate a decent-sized room to be cut out of it for each of his requirements, but set a burrow (or several) for the entrance and the outer limits first, then designate the miners to these burrows according to taste. The outer-ring of the rooms will get cut out first and (assuming you haven't inadvertently hit cavern void at all, which you should hopefull be able to plan against anyway) send in the engravers to smooth the walls and the outer bit of floor. (Engraving also possible, but I rarely bother, to be honest, unless the room needs a
slight sprucing up, then I start with the four corners, and add as necessary.)
I tend to put my bed or sarcophagus or chair that designates the room-type (or the chair that will sit
next to the table that designates the dining room) against the far wall from the door, as soon as that tile is smoothed (and, if you're so inclined, engraved?). Adding the spot the dining-room table will stand to the perimeter burrow is something you may or may not need to arrange at this point, depending on the speed of the remaining process.
But, by the time you've gotten the furniture (and doors[2]) in place you've almost certainly added the central rock-filled bit of the room to the mining-burrow(s) concerned, and may even have finished it. Designate the room as soon as you can, but go back to make sure the old designation fills the room, given you'll have first set it up with rock-pillar still in the centre.
I tend to put my 'auxiliary' furniture (cabinets, chests, armor stands, weapon racks and any other special request) strategically/aesthetically around the edges (and as logically as possible to the room's function[3]), which by now should be fully-smoothed by the army of idlers that you drafted into the engraving job, and that now you've got smoothing (and engraving?) the open centre of the floor as well, doubtless.
But let yourself be guided by your own design goals, in all aspects of these Great Works. (Also whether, in the fine traditions of the Dwarf Fortress community you additionally make provision for
magma flooding easily activated central heating of the royal apartments.)
[1] Burrow-designating one layer at a time to avoid silly moves that would result in cave-ins.
[2] Pro-tip: a door 'construction site' will terminate a room designation exactly the same as an actual door (that is not set to "internal", of course). Even if you don't have the Masterwork Doors Of The Resident's Favourite Material immediately at hand, you can arrange for a random door to be built on that spot while you're designating room limits, if it would help extend the room out towards the entrance but you don't want the area 'leaking' into side-chambers. Then you stop the door from being built, but the area will (until and unless you attempt to resize it) still terminate at that pinch-point. Once you have the Doors To Die For, you can set them to be built on their respective spots and let that be construction duty be fulfilled to comnpletion, as normal.
(Until doors and auxiliary furniture is emplaced, it will not count towards room value, but it will add to the "I haz a cabinet"-type count, as appropriate, so temporary designation of so-so substitutes (perhaps suspended, if you want to avoid the hassle of deconstruction just before the switch to the good stuff) may stave off
some of the bad thoughts the noble might have, although the room-quality ones are still reliant on what is actually
there, and/or carved.)[/2]
[3] So the (first) cabinet and chest tends to go in the bedroom, before spreading into the other rooms; the first required weapon rack and armour stand each sit in the office/dining-room (one way or another) and subsequent ones complement their opposite numbers. The most difficult room to 'furnish' is a tomb, when required, assuming you aren't just going to plonk a set of statues down in there, but a spare stone coffer (and I never fulfil the 'container' requirement with just a bag!) probably has its place in there, as if for grave-goods for the guy who may, or may not, eventually inhabit the coffin or sarcophagus that defines the room. Racks and stands could work in there. I've never liked putting cabinets in there. Doesn't seem right. Even if there are spare Masterwork ones, tables and chairs don't seem right to me. But, then again, I've never really seriously considered that I would
personally need anywhere to sit and eat, after I've passed over and my entire contingent of other-worldly goods is sourced purely from the catacombs that I've been sealed within, so maybe I've been missing something.