Heyo!!

I've stumbled upon an issue or misunderstanding with preparing my documents for Finland population data services.

To be certain - with a process of getting kotikunta. I'm in the process of moving rn (recently I've gotten a permit to stay, type A, for a year) and.... Well... what actually is needed to get kotikunta? I'm not sure. I have not found any certain info about what exact documents are needed to get kotikunta. Like....rent contract? Is it possible to use a hotel for those purposes? If yes, how long should I stay in Hotel? Orrrrrrr is it just like ummm... formality and I can use the post office address for getting documents poste restante? Or I don't need any documents or proofs at all and I just can sign up for any municipality I've chosen?
The issue is since im in a process of moving I still need to make all of these documents before the actual move. And it will not be very nice to rent apartments which I will not use before my move in several months and I need all the documents beforehand, so..


I would be very glad for any tiny bit of info!
I've read a lot of sites and articles and some of them say I must bring some docs, others say I can register it even without any living address.

I've also asked in DVV and migration service but they not answering me so far so i've decided to ask here >3<

Thanks everyone in advance!