How long after stopping can I become pregnant?

I have been taking Aviane for 1 year now and I was wondering how long it would take before I can actually become pregnant? I only have until the end of this month of July and then I plan on not refilling the new prescription I got because I want a baby, but I want to know if I could become pregnant immediately or if it's going to take a few months to get pregnant?

Also, I do have a new prescription for Ortho Tricylcen which I can refill by the end of this month, if I decide to keep taking them, but will the brand change affect anything or is it the same effects?