I haven't got a BFP, but I had my first + opks these past couple of days. The last two months I thought I missed my surge, but now I know what I was doing wrong.
I have been using the Rite-Aid brand sticks. There are 20 in a pack for about $18... Kinda pricey, but worth it. The last two months I have been testing in the morning. Well, I read that you usually get your LH surge in the early morning hours, so the best time to test in from 11am-5pm. I tested yesterday at 4pm and a strong positive... The directions say to use FMU, which you can do, but I suggest following up in the afternoon with another test...
Get some preseed while you're at. That stuff is AMAZING!