It depends on your body, but I think many people begin surging sometime in the AM and will register a positive around 2pm. If this is your first time using OPKs, I'd recommend testing multiple times a day to make sure you don't miss your surge! Some people only surge for a couple of hours. My surges last 1.5-2 days, so by now I know that I'm okay testing once a day (usually when I get home from work, around 5pm).
Faint line = negative. With OPKs, you want a test line that is as dark as, or darker than, the control line. (It's not like preggo tests, where any line is positive
).
Best of luck getting those +OPKs, everyone! MrsWez, it looks like yours is really close! I would start BD tonight if I were you!