Historically, how long does it take for MBP/MBA to reach the refurbished store after release? From the previous releases of the MacBook Air and MacBook Pro, how long is the gap between the devices being released and appearing on the Apple refurbished website?
It can happen any time after the first machine exits the initial 90 day phone warranty. As soon as Apple has a used machine returned to them, it will be reformatted, cleaned up, and repackaged. Once Apple has enough to sell again, they go on sale as refurbished models.