I've heard rumors/suggestions that you shouldn't worry too much about things until you have a clear revenue or expense plan that reaches the IRS minimums: https://www.irs.gov/individuals/check-if-you-need-to-file-a-... ie: if you're making $100/mo (talk to your tax advisor), but if you're clearly making $3k+/mo then you should have a plan to incorporate, file taxes, etc. (and should also be talking to your tax adviso…
However, we thought that starting a company would motivate us because we would be "commited" and this would demonstrate to each other that we were serious about it, given that we all had other jobs. And to this day, I still think it has some meaning.