Ovulation question

Alicia • Mom to a 14 yo boy and 8 yo girl. One 👼🏻 11/2010.

I never used OPK with my 2 kids, but I was young and it was easy. Now I’m 34 and feel I need to pay attention. Last month failed but I didn’t start tracking til the middle of the fertile week that was projected. I just got Pregmate strips and my cycle is due to stop Tuesday/Wednesday, but I think it may stop a day or so early. When should I start testing for ovulation and temping??