I went straight from Synarel into a fresh IVF cycle, and AF started a few weeks later (we got a BFN), so only a couple of weeks between the two, but that was with the help of Puregon injections also.

I assume you're using the Synarel as a treatment for endo, rather than as part of an IVF cycle?

I've been prescribed Provera (progesteron) to bring on AF, but I've got PCOS, not endo, so I'm not sure if it would be different in your situation.