Two partners and I just opened a nano and are holding our initial release parties in about two weeks at two different bars... so... I just went through this.
You're going to need to file for and obtain a Brewer's Notice through the TTB. Part of that application process includes documenting the commercial space you've OBTAINED (not "are looking at"... they want a copy of either the deed to the property or the executed lease agreement with the landlord.) They'll also want proof of insurance (the landlord will want that too), six months of financial records, evidence of where the funding for the brewery is coming from... among other things. We were able to get all of that paperwork filled out and submitted in about two weeks. We got approval in about 45 days after that (which was lightning fast from what other breweries have told us).
Once you have your Brewer's Notice, then you have to get your state license... the state is typically dependant on getting the TTB license first. State licenses vary dramatically from state to state in terms of rights to self-distribute, tasting rooms, ABV limits, fees, etc. I can't really help you there other than to say that I can't fathom the state not having a detailed process for all of that. That process here in Mass took us another 75 days or so.
(all the while paying rent on the commercial space we had to take)
While you are going through the licensing process, you get the pleasure of dealing with local/town building/fire/electrical/plumbing inspectors as well as the Board of Health. YAYYYYYYY!!!
They're going to want to take a look at every single nut and bolt of the brewing operation. We were originally going to use banjo burners.... NOPE... "not UL or any other industry safety commission certified. Sorry". (trust me, I know how ridiculous that sentence is). We had to replace our stand, our burners, everything but the pots. "oh...well... the natural gas line in this building isn't rated for the volume of gas you need so you need to run new gas line"... $2,600 to run black pipe across an entire building.
And it just keeps on coming. ADA-compliant bathrooms... "sorry, you need a new toilet, sink and this door isn't wide enough". CO monitors and automatic gas shutoffs. Water backflow preventers so you don't backflow into the town water supple (again... ridiculous but we had to do it). Make sure the septic tank is rated appropriately. If it is sewer, make sure the town is Ok with "brewing chemicals" being dumped into the sewer. Occupancy permits, business permits, LLC registration... don't forget you ge the pleasure of now filing corp. taxes too as well as your state and federal excise tax pre-payments!!
I am really skeptical on the corny route but ya never know.
We're on a 1.5 bbl system and while we ABSOLUTELY knew this going in, at that scale, it is impossible to make any money. We can work around the clock if we want and sell every drop and at the end of the year, each one of us would make a couple grand. If you are brewing on a 15 gallon rig, take that tiny profit and erase it completely.
Start to finish... it took us about 14-15 months to get from "let's find some space and do this" to "Our beers are going on tap in two weeks!"