Can Ovulation dates vary by a lot?

Ch

Hello! I’m on my second round of clomid. First round my ovulation tests said I peaked in day 17 of my cycle now I’m day 16 and not even a smidge of a detection. I honestly didn’t start testing until a couple days after my period because that’s what it was like the previous month and that’s how I ‘normally’ am.

Thoughts? What are your experiences?