Today is actually CD21 for me, I normally ovulate CD18 but this time it was a little late. My friend told me that you have 3 fertile days as soon as you get a positive OPK so I am crossing my fingers and toes!!! BD today, tomorrow and Wednesday, then the dreaded 2WW
Yes tonite is a good time to BD. And tomorrow . Even though you are CD18 there's a chance you did not miss it. Your OPKs are going to show pos for a few days and this may be a little misleading so now there is no need to contnue testing once you get a pos. Next cycle, test every day from CD 12 to CD20 as some women have late ovulation, depending on your cycle.
I say it is worth a shot. U never know!!