Welcome to BB! Good luck with your TTC journey.

I haven't heard of a dr saying to wait 3 mths before trying before. I'm not a dr though so there might be a reason for it. I would think just go for it and see what happens unless there is a medical reason to wait. Maybe he wants to run some tests? You can start charting anytime. I think the best time to start is on the first day of your period but anytime is fine. There is a website called Fertility Friend that a lot of ladies in here use to help chart their cycles. It might take a while for your body to get back into sync. I have heard it can take up to 12 months but that is rare. Most women go back to normal straight away. If you're not on the pill now, then this would count as a real cycle. You could also join a TTC Buddies thread if you want to! They are a great bunch of ladies going through the same thing and are excellent for support & answering random questions.