Need help with timing please!

I've gotten negative OPKs for days, even up until about 5 hours ago, they have been completely faint. I just got a pretty positive opk tonight at 7:30pm (CD 11) so I know I've caught the beginning of the surge. My husband and I BD last night already. I would just BD the next 3 nights to play it safe but we did that last month and got BFN, so I don't know if my husbands swimmers can handle every night : / should we BD again tonight or would we be safe to BD tomorrow and the next night since I'm pretty sure I've just caught the beginning of my surge now?