Do you guys request letter of recommendation right after say shadowing the doctor or do you wait until you are about to apply and then ask for one? Thank you.
I'd ask right after I was done, provided that I was actually done for good. You want the longest possible chance to make a good impression. That way how great I am is still fresh in the doc's mind.
The doctor isn't going to recall you in a year. Life moves on. Get the reference soon after leaving. You are unlikely to be asked for a physican reference anyway unless for a committee letter or if you apply to DO schools.