@Tyye thank you!
Typical cycles are 28 days. Most apps will estimate that until you’ve logged enough that it averages yours out and estimates your ovulation. I used the Premom app, which was free at the time. I would also recommend buying some ovulation test strips. I used to buy mine from Amazon easy@home sells multipacks with pregnancy and ovulation tests, and they’re not that expensive. Most pregnancy tests will be accurate 14 days post ovulation. Some of the early tests can pick it up as soon as 10 dpo.
I did mine 4days to my period and it showed positive but a blur line
two weeks from having sex