No limit.

From a practical standpoint, new-hires need to have accounts setup in the computer system to enter bids and this usually occurs in the first couple days of indoc.

And a vacancy bid "effective date" is typically several months in the future so even if a new-hire is awarded a different base on the first day, it's possible that one could finish training, complete IOE, and fly a month (or more) in the original base before going to the new base.