Level 1

Passion Project about to turn to Self-Employed?

I've been working on a passion project for a few years, without income, and potentially will soon start gaining an income. The lead of the project lives in another country, and says due to the employment rules of the country when he's able to pay us it'll be "contractor" type pay, which seems to come under "self-employment". 


I've spent the past several hours researching, figuring out what my state taxes and federal taxes would be, finding out about the self-employment tax, and something about quarterly payments... The amount of pages of tax information and that information leading to other information and just endless pages that seem like they're just trying to make a person mess up their first time..


Can I get some help on what exactly I should be doing? If I start making an income this or next month, do I file the federal and state taxes for this year next year? When do I file self-employment taxes and start paying quarterly? How am I supposed to "estimate annual income" if my income will potentially be unstable?