Ovulation Question

My first baby was conceived and we weren’t using ovulation sticks. I am trying for #2 and trying to get the hang of them. Can anyone tell me a couple things...

I’ve been tracking a couple months. Is it possible to have peak results on different days each month? Last month it was day 16 and this month it seemed to be on day 13. My cycles are always the same length. 30days. I am new to this so any info would be appreciate. (If this is a dumb question im sorry ahha)

When it hits the peak on the ovulation test. Are you already ovulating or are you going to ovulate? I don’t know if I should keep trying after those peaks or focus more before?

Thanks ladies!