US Postal Service Associate Rural Carrier interview questions

Applied to multiple positions RCA and CCA Received email to schedule 473 Exam Took the exam and got a passing score Interviewed for RCA first (Offered job on the spot - Offer Phase EXT) Submitted MVR and background check Accepted offer letter Took and passed drug test Interviewed for CCA (Awaiting Feedback on Prehire status) Fingerprinting and processing coming up for RCA in the coming days as of this post My question is that I have a good chance of getting CCA and would prefer to have that one since it's at a PO closer to me then the RCA. Is it an issue to transfer over the background checks, do I have to quit prior to training for RCA? I know the training varies for both RCA and CCA and not sure what to do.

One hour going over details of the job and a few basic questions. Mostly making sure I understood the job functions and was up for it. Thus, if hired, there would be less likelihood of being shocked or overwhelmed and quitting.