Prenatal vitamins

So I haven't gone to the doctor I will be going today in the afternoon, but should I have already started taking prenatal vitamins? If so does it matter what kind? Or do I have to talk to my doctor about it? I know I have to set up a prenatal appointment is that when I wait or what lol, I'm just really hoping I get everything on track, this is my first pregnancy and I'm like not thinking straight because I'm still in shock!