You'll probably know better than me how it works, but I'd assume they start selling from the North section first and work round so that it looks better on the tv? This way they can show viewers full stands and it looks like a fair even split, as any unsold seats will mostly be out of view of the camera.
My mate is a ST holder who goes to as many games as possible. He is concerned that he will miss the final. And yet he received an email from Aberdeen offering him the chance to buy 2 tickets in the Aberdeen end even though it was many years ago when he registered with AFC for a game up here and hasn't used it for a long long time.
There are 4 tiers of AFC supporters, the top 3 tiers can each buy 4 tickets each (3 of them can be for absolutely any Tom, Dick & Harry that don't need to go to any matches) and he was in the 4th tier - so never attending an Aberdeen game in years makes him qualified to buy 2 tickets! He is swithering about buying from AFC just in case, but he knows he'd shout out about the mutton molesters very quickly or grassed up by someone who knew his allegiances and he'd be chucked out very quickly or given a hiding.