Normal, usually two to three weeks. But stop watering it because it wilted.
A peace lily that flops with damp soil is not thirsty, it has fewer working roots than leaves right now because fine roots tore during the repot. Watering into that raises the rot risk and does not fix the flop. Water on the soil's schedule, not the leaf's.
Things that shorten the sulk:
- keep it out of direct sun for a couple of weeks, bright shade only
- remove one or two of the largest older leaves so there is less to support
- no fertiliser for at least six weeks, the roots cannot use it
- a clear bag propped loosely over the top for five days raises humidity and cuts the afternoon collapse noticeably
If it is still flopping daily at four weeks, tip it out and look at the roots.