I've done my taxes in school meetings. It's doable if your financial situation is simple, which I'd have to expect as a 20 year old it would be. If American, well, the 1040EZ form is called EZ for a reason. You can dash that out in a few minutes with your pay stubs around.
90% of doing your taxes is rounding up the documents you need. First time through you'll hit a lot of places where you go "Oh wait, I didn't realize I need that" and have to go look up stuff.
I'd suggest doing it at home on paper the first time. You might as well take the time and learn it properly since you'll be doing it 50-80 more times in your life… more if you start a company.
A short form 1040A or 1040 takes no time at all. The time is imputing your name,etc. I would do it at home. It can be done inside of an hour but you could encounter questions you aren't prepared for. You can begin it and save it. When you get home just put in your user name and password and continue from there.
Takes me about 15 minutes
It depends how long you want it
