Ovulation

Hi guys, so my period ended on the 15th of this month. I had a normal 5 day cycle and my expected ovulation day is 12 days from now. My boyfriend lives out of town and I’m trying to conceive when I see him. I’m leaving on the 23rd or 24th of this month to see him and my fertile window will start around that time , my question is should I start immediately and definitely on my ovulation day? First time trying!