AF is supposed to come today!

So Ovia says AF is due today. And she hasn't shown yet. Glow says Thursday...the last 3 cycles I have spotted a few days before she had arrived and I haven't yet. I am wondering if I should test today cu Ovia says I can or wait it out til Thursday! I'm nervous because I am having surgery to repair my septate in my uterus Tuesday! So I'm hoping for AF this month...I'm kinda stressing! Help!! Which test is best for early detection!