I am planning on doing this, but I need to find the right time to do it?

Okay well next week I am planning on asking out this really cute hispanic girl and giving her a flower, but the problem is, I can never find the chance to do it.For one she is in none of my classes and the only time I really like would get to talk to her would be like at lunch.And plus she is always busy and stuff.But I really wan't to do this next week and I am planning on doing it.What would be a good time for me to do it at?