I refused to see a doctor until I was 12 weeks and confirmed my pg by u/s at 15 weeks. I booked into the hospital of my choice at 22 weeks. I also got in to see the OB of my choice at 20 weeks. I left everything until the last minute really but managed to get what I wanted, thank goodness. I would probably ring the hospital and OB you want to go to and see when they recommend you book in and if they think booking in after 3 months is ok.