Can I change from active to Reserve while in DEP?HELP!!!!!?

I only signed the contract in mEPS and took the oath, I know it is not final until actually your ship date which is in 05/05/08 , but I want to cchange jobs and i want to go from active to reserve now please help??? And how long will it take for my recuireter to do that ? Will I have to go to MEPS again and speak to a job clifier again, Please help!!!