The problem is overnight stands. I would expect they would be used as soon as they were put in use, first come first served.
That’s assuming that there is that much pent up demand from the airlines for new overnight stands from day one. It might be a long process to fill those stands. Stansted has plenty of spare capacity which is just sitting there.
Some of those spare stands are already available as Ocean Sky only occupies part of the South Apron. Maybe by the end of the year the whole southern apron will return to airline use but without the terminal extension and particularly the extra security lanes could those stands be used for night stoppers for another couple of years?
If all the 15 new stands are filled then it is likely to come from Easyjet or Ryanair moving some services from Stansted. Easyjet have already stated what they expect from an expanded Luton including more non-stop trains from London via East Midland Trains and the shuttle bus being made free again although if £1 or so was added to the train fare to pay for the shuttle no one would notice.
Also there were plans from the council to extend the new pier to the south apron, is that still the case or has that been dropped?