I'm going to flake on my study/presentation group to go on a date with a guy I've had a crush on for almost a year
Do you think that this might be an important first date?
It depends. Yes, if it feels right.
While it is not the most moral thing to skip a study group for a date, it does make sense. This is a pretty nice opportunity if you have had a crush on this person for so long. Just make sure to let your group know that you wont be there so you can make up your part of the work.
Lol, I have that covered.
In that case, I hope everything goes well for you on your date.  As long as your study group know that you won't be there, and that you will still finish your part of the work, then missing one meeting shouldn't be a problem.