When does bbt decrease if not pregnant?

Tessie

My bbt has been all over the place since i got my cycle back at 8 months postpartum. When should my temp decrease if i am not pregnant? I typically have a 12 day luteal phase, but am still having a hard time waiting to test! Last time I got a BFP on 11DPO, but I don’t want to wait until Thursday 🤦🏻‍♀️