First time trying OPK, need help on cycle length

Korey • First time 🤰🏼baby girl 🎀 Hanna 11/10/19 💍 5/11/18
Hello,
We’ve been TTC since September. Prior I had been on birth control since age 18 (I’m 32). No kids. I’ve been tracking period and we’ve been having lots of sex all month but especially during the fertile week. He has 2 kids. So since it didn’t happen right away, I’m freaking a little. I just want to make sure I’m ovulating. I bought the digital test kit (the strips always confuse me and aren’t straightforward enough for my liking). My question is, what day I should start testing? My previous cycle lengths are 29, 30, 27, 26, 26. Should I start tomorrow? CD10? I bought 20 tests. I basically just want to make sure I’m ovulating so I have piece of mind nothing is wrong. Also planning on checking BBT as well. Any advice? Thank you!