"real" security clearance?

i'm in DEP and my navy recruiter told me i was cleared and sec. clearance granted, but upon further research of my own, i found that they apparently don't start a real investigation until slightly before one finishes boot camp. Is this true? did my recruiter lie to make me feel better? i'm going in for a specific rate and if there is a possibility that i can't get it, due to the disapproval, i want out. so what's my recruiter's damage? given that the info i obtained is true...