OPK question

Faye
How soon can an OPK go from peak ovulation to past ovulation. I use Fertility Friend to track, which records a positive OPK as peak fertility for the following day. 
The top test is from this morning - The test line is definitely darker than the control line. SO and I bedded after testing. The bottom test is 10 hours later and is definitely lighter. 
Should I assume I hit peak during the night, and may have missed out for this month considering it would take a few hours for his sperm to reach the target?