hoping for the rainbow this month... Trying OPKS!!

After MC in July... I'm just hoping my cycle finally gets back to something normal. In August af was right on schedule, but longer than normal. September brought uncertainty with an early super light and short af... Wasn't sure if that was just spotting. And October was an early surprise but everything seems normal so far, started the 2nd. I decided other than to track by calendar I will enter into the world of OPKs. I ordered them and look forward to their arrival. But I'm worried I won't be using them correctly. And once you do use them, on average how long did it take before you got a BFP? Any tips ladies? At 41, I'm certainly not getting any younger, no time to spare...