Should DTD again?

steffanie • 29, ttc for the first time. I`m into video games, reading, tv and general malarkey
Had positive opk yesterday and this morning. Looks negative now so I assume the surge is over. Had some twinges today. Had sex Saturday and yesterday. Planning on doing the deed again tomorrow as I'm exhausted today. Would this be too late? I've read you ovulate 24-48 hours after the surge so I assume I'd be OK to skip tonight as sperm can live up to 5 days?