Can someone please help?


So I was lucky enough to be able to have two children one is 10 and one it is 7, but I was not TTC when that had happened but i was blessed with them, I also have a step son who is 2 now. Im almost 30 but me and mine are TTC but havent started <a href="">tracking ovulation</a> just been going off of apps(which i know isnt legit enough) so if someone could please help me and let me know how long after AF should i take an opk and for how long? And which app is good to detect peak? Ive been reading alot of stories and getting information but would like some more insight if you can help please and thank you.