First come, First served.
There's currently 4 FO's waiting for a transfer to EDI, and 3 waiting for GLA.
Between the two bases, there are 5 FO's on the transfer list to leave, so there will be movement, but as the base isn't really expanding, it's a case of how long is a piece of string?
If you're a new joiner - you'll be in the queue behind the above 7 (in theory!)