I guess I can't just say 'don't worry about it', since that wouldn't really help. I know the struggle all too well from my beginning days.
Since it doesn't sound like it comes from a place of anxiety, I assume what you're feeling is excitement- you are excited to see if your spell has worked. You're anticipating it. Excitement can be as hard to work with as anxiety, but I'll try to help.
I would suggest you find something to distract yourself, or you could also try mediation. I find that sitting down and thinking, "My spell is working/has worked. I do not need to worry about it anymore," and accepting it, letting that feeling really sink in, helps a lot.