I find that a particularly useful feature. Once the migrant wave is 'decided' (I get a hefty lag-pause whenever that sort of thing happens, in my setup - from DF, that is, not a complaint about DT) I immediately review all newcomers and pre-arrange their active skills upon arrival, rather than the 'super-vanilla' method of keeping the cursor around the migrant-entry edgepoint and editing 'live' as each new non-child/non-pet arrival shows up... which can be a couple of dozen or maybe more such individuals.
The only problem I have is that I habitually de-Hunterise hunters (ditto fisherdwarves, but without this issue) which leads to having to visit the edge-spot once they've all arrived and specially arrange (to speed up the usual stock-movement, by using the parallel Dump-designation that seems easier to prioritise) that the immediately-dropped crossbows and quivers are brought into a handier 'internal' location. But that's usually better than having stray hunters going wandering around the map again as soon as they've fulfilled their desire to report to the Meeting Area/whatever.
IOW, very normal. You can always just ignore them until they're properly on-map or even properly in-fort, if not until you decide their arrival settings need changing, or do as I do and 'cheat' a little (it's more just a time-saver - at least for me, who spends so much time on Pause for various other micromanagement reasons
).
(I unset Corpse Hauling for all 'processed' individuals, as a handy flag (except on the rare occasion I need a corpse hauling, which is usually not coincident to an incoming wave so can be tagged temporarily as required without upsetting this system), plus assign a nickname (so the nicknameless are the same set). Though I'm fairly sure there's a wave-of-arrival order/group setting (that I just don't personally use, sorry, but I can see its usefulness) that can cue you in on the latest (possibly not on-map) arrivals if you have no other system in place.)