[avasmom603]

When do you start POS? I got AF on Saturday morning and she's already gone. I had POS for my DD years ago and got a BFP on the first day of testing - day 11. When should I start?

also, what does a temp drop mean after AF? Is that typical? My temp plummeted this morning.

One more question... if I get a BFP on the OPK does that mean I have to BD that day? That's what we did with DD and in just one try she was conceived. I keep hearing one to two days after the BFP, but that wasn't the case in the past.

[Halfbaked]

It depends on how long your cycle usually is. Personally, I start on cd10 but my cycles are usually 31days long. If your cycles are shorter, you start sooner. You could start now and watch the lines get darker. I do it morning and afternoon when my lines start getting darker just so I don't miss it.
For your best chances, you want to bd before you O. Some say every other day until a positive opk and then every day around O to increase your chances. Unless you're temping, it's hard to tell exactly when you ovulate so a few days after should cover it. Good luck.