WIBTA if I quit an unpaid job right before it began for a paid one?

I applied for and was accepted to a summer camp earlier this year. My mom required me to work this summer and it was all I could find. The camp is unpaid and 40 hours a week.

I just got an email about a camp that teaches one of my hobbies. I was recommended by another hobbiest I know. The camp is paid and 35 hours a week.

The paid camp wants to interview me this afternoon. The unpaid camp is supposed to have a a meeting tonight. I would probably know if I 100% had the job before the meeting.

If I 100% have the paid job, I'd like to quit the unpaid one in favor of it. I not, I would attend the unpaid meeting and continue to act like I'll work until I know for sure.

Is this an acceptable thing to do? I don't want to be a jerk!!! I don't know the etiquette for this stuff.