Ovulation Question....help?

Hey ladies, just a quick question. I'm on cycle day 15, just receieved my positive result on my ovulation test this morning at 5am. I had sex on cycle day 12...which was Thursday. Im positive I can not have sex tonight. My boyfriend already announced how sleepy he is lol. So would Thursdays sex session be good enough. Do you think the spermies can survive 4 days! Oh I hate this, or should I at least try to get some in the morning before he leaves for work? I hate when he is too tired for sex when Im dropping my egg! I'm sure you ladies can relate...😣