Congrats on the decision to do a house hack!
My wife and I purchased a 3 family property 5 years back and have just finished renovating all 3 units. We have lived in one of the units and rented out the other 2 the whole time we have owned it. We are now planning on purchasing a single family and renting out the 3rd unit as we move out.
Couple of things I did or wish I had done...
1. Purchase the property under an LLC to begin with. I didn't do that and I now regret it. If I wanted to roll it into an LLC now I believe I would need to pay the 1.5% transfer tax. The LLC origination fee is quite small and will provide you with additional protections should you move on and buy more properties in the future (as in my case). Also helps keep things organized from a personal finance perspective.
2. Keeping property and personal expenses separated is really important from an organizational stand point. Setup separate bank account and credit card for the property. I did this and it makes my finances much easier to interpret moving forward. I originally shared my personal credit card with the house and I regret that. Its hard to do your personal budget when you have a ton of home improvement costs mixed in (as in my case renovating the whole house myself). I now have dedicated credit cards and banking accounts for both. Treat yourself as a Tennant. I pay my mortgage and any utility bills via the house bank account and then have an automatic transfer from my personal checking account each month to "pay myself rent". It is important to include a vacancy and repairs retainer, some people recommend 25% of your annual property expense but I consider that a bit high for my case. We live in a desirable town and have managed a total of 15 days vacancy over 5 years between 3 units.
4. Allocate a percentage of the property to personal and investment. In my case with a 3 unit I do 1/3 personal and 2/3 investment. Any expenses incurred for the property as a whole go in as a 2/3 depreciation (whole house systems, yard improvements/maintenance, exterior improvements, etc.).
5. Diligently save/document and expenses incurred improving your unit and the property. When you move out and rent the final unit you can begin depreciating these expenses as if it was day 1. In my example, I have spent $125k on improvements to the property as a whole. Approximately $25k of that was spent on the rented units, $30k on the property, and $70k on my unit. I have already begun depreciating the $25k plus 2/3rd of the $30k, but haven't been able to claim any of the remaining $10k + $70k. That means that when I move out and rent my unit I can add $80k to my depreciation schedule. I track everything in an excel sheet and save all my receipts in annual folders.
Disclaimer: I am not a professional and this is really opinion so please fact check me before making your own decisions.
Good luck, nothing like having somebody else pay your mortgage :)
-Tim