It varies. Some programs will send them to you right away and others will send them out a little later on. Mine sent me one towards the end of April before internship but every year after that it wasn't until May or June.
Expect to be contacted by your program about applying for a medical license---those are much more time-sensitive as it can take 1-3 months (or more, but usually not for someone just graduating med school) depending on the state. They will tell you any state licensing deadlines you need to follow.