At what point? There is no point. You have to APPLY - go through a whole NEW interview process and group exercises even if you have flown for eJ for 3 or more years. These aren't hoops either. People fail at this stage and remain a flexicrew pilot. None of the roster is fixed.
Please also be aware that the future is not permanent contracts at easyJet. eJ don't want it, CTC/OAA don't want it because they get a cut from your flexicrew salary. eJ is becoming Ryanair - expect to pay for everything and get nothing. Expect in 3 years to have contract Captains, no permanent FO's and further degradations to working conditions.