Tryiny to conceive

So june 17 2019 I toke the birth control out of my arm I got my first period on july 17 I think this app say my next period is suppose to be on August 14 Im late the prediction is sometimes right either I get it when Im suppose to or I be one day late. So today marks the third day now I have three kids and usually on the third day I dont get my period should I get a pregnancy test or wait a week to get one. I had sex once my period was and I was ovulation on july 31.