Which App to go off??

So I use and pay for Natural Cycles and it’s always dead on with my AF.

When we are TTC I download Ovia and now Glow. However they are all say I’m due AF on different days etc.

NC - AF due 14th Oct says to test 17th Oct

Glow - AF due 17th doesn’t say when to test

Ovia - AF due 19th says to test 15th

What the hell?!? Haha don’t know what to do! With my last pregnancy I tested off Ovia’s prompt and I was 12DPO. My previous pregnancy I went off My own intuition. Help! Haha 🤷🏻‍♀️🤦🏻‍♀️