When to visit doctors office ?

I'm 17 years old, I recently found out a week ago I was pregnant. I'm 5weeks4 days as of today. The nurse at the clinic offered me to go back on January 31st for an ultrasound. He gave me a list of hospitals and doctors and OBGYN's and Midwifes. But, when should I go to the doctors? The clinic I went to is really just for pregnancy testing. I don't have insurance at the moment, but I do work and save money so I can try paying for the appointments like that. Any advice ?