In my own attempt at this, yesterday, i started by throwing three out of four "armies" (as in groups of 4 units each) on Sweds from turn 0, and bumrushed recruitment of Line Infantry in Warshau. You can easily capture Swed territory up until Finland early on (just make sure to merge before starting the invasion), and both cripple a powerful foe, and secure the entire east block.
From there, each enemy - except for Prussia - has only one way of getting to you.
Austria via Breslau, Ottomans via the fort in the south, Sweds via Finnish wastelands (They attack Denmark most often, instead of you)
Don't bother with a navy, and Swed navy will be of no concern - since they start with a war with everyone.
Thus, this is what i suggest. Prussians will, naturally, attack us sooner or later, but taking Konigsberg and curbstomping Prussians will be much easier without the threat of Sweds. Taking Sweden itself and Norway that early seems like a waste of time, and unnecessary longer front line. Halting at FInland allows your Russian allies to attack Sweds too. Should Russians capture Sweden and Norway, they will be of help to you for more wars, than just the one against Ottomans.
Ideally Prussians will be at war with Austria eventually.. Ideally... This is not to say that this war will weaken any of them, but with Austria as a threat, Konigsberg will have a lighter garrison.
My progress was slowed down by the fact, that i've discovered how to build schools in late 1720's, so i'll be starting a new campaign. It is, however, definitely possible to do much more.
What i've noticed is, as follows :
- AI doesn't just declare war on you "Because you're the player"
- As long as you keep your upkeep < (income - trade income), you can completely ignore navy.
- Combat AI is completely braindead.