I want to get back on the pill but I'm a week late for my period

Ok so I was on the pill for about a year, I just got off of it in June. Now I am seeing someone new and I want to get back on it, so I figured I would wait until I got my period in October and take it the Sunday after. The problem is that I am a week late for my period...but I took three pregnancy tests all resulted in negative. So should I wait until I get my period before going back on the pill or is it ok if I begin it this Sunday like I had planned to do as if I got my period.

Thanks in advance for anyone who responds it will help a lot!! :-)