I think you should expect the unexpected. When I came off the pill after years of use it took a few months to get back into a true routine with odd spotting here and there and funny mini periods between the expected ones. After a few months it will settle down, or much earlier if you are lucky. Good luck ttc!
I've been off the Pill for almost 8 months and it that time have had just two periods!
Everyone's body reacts differently to the Pill so what happens to one person may not be the case for another.
As long as you are not bleeding too heavily I would give it a few months before seeking advice from a GP. My GP told me to come back if nothing had changed after 6 months - it hasn't so I'm off to see her again next week!
I took the pill for 8 years and had no periods whatsoever (I needed to suppress ovulation due to endometriosis) I came off the pill a couple of weeks before my wedding, got married on the Friday and was pregnant by the Monday! I had no idea of my cycle and it was a massive, yet welcome shock. I'm ttc again now and just got my period today so will be checking in here regularly, good luck.