I applied quite early after the job was posted, then heard back about a week after the applications for Aberdeen closed. Since the Edinburgh apps are still open, I doubt anyone will hear until after they close. I'm guessing it will take awhile to hear back based on assessment centre dates and attendance numbers.
Disclaimer:
I don't know if this is how ScotRail will be doing things so pinch of salt here:
I worked in recruitment for awhile and the way we did it was with a stoplight system--'green' are the people who are invited to AC first, we did it in the order that we received the applications within the green band. We filled our earliest ACs with all of the 'green' people first, then if there were extra spaces in the ACs and our numbers weren't on target to meet predicted conversion rates, we'd offer the spots to 'amber' people. 'Amber' people who made the cut would also be offered later AC slots if the success rates at the first ACs were poor, or potentially last minute slots from last minute drop outs. 'Red' people got rejected almost immediately after their applications were viewed.
Long story short, if you don't hear back within a week or two after the closing date, it would be a decent assumption that you've been amber-banded, so it could be awhile before you hear back. Straight up rejections from the application would be pretty quick because it will be people who didn't meet the base criteria.
