Hmmm... I've got a question for you ladies

So, I've been on Metformin for about a week and a half. I think I'm about to start my period, I had very light spotting today. I'm supposed to call my doctor to let her know when AF comes so she can send in my prescription for the pill to the pharmacy. Since it's Friday, if AF does start this weekend then I won't be able to start the pill if I don't call. Should I just call to be on the safe side?