pregnancy 1st appointment question

Hi so I just found out I'm pregnant! It's my first and I just had a friend tell me it's a good idea to start stocking up on things such as diapers, baby powder, shampoo etc. but I'm only 7 weeks and my first doctor appointment is on the 20th. When did all of you start buying stuff for your baby and also could someone tell me what happens at your first appointment I'm super nervous!😅