Mine was a IG vinyl pool (18x36), w/ tons of extras. Brick coping/edging at ALL corners had to be redone, which set us back 4 weeks.

Schedule was as follows:
5% at signing contract
55% when hole dug (on a Tuesday)
30% when liner in and water in pool (by Friday)
10% upon completion: coping, deck, ladders, diving board, water level maintained and filter running......basically able to swim.
*****originally had stated only that completion was 'filled w/ water and filter running' which means cleared by inspector. We said no to that, as brick redo and then cement decking was delayed. Builder was fine w/ this change in original contract.

Good luck.

CaryB