As your plant grows the leaves will fluctuate up and down as it grows. Also depending on its light cycle. If it is about lights out they will get droopy as well. But generally droopy leaves is a moisture indicator. Either too much or not enough. More perlite in substrate can improve the plants resistant greatly to too much water. Making watering a lot easier and safer. A way to judge how much water is in soil is pick it up. Water is heavy. Will be a noticable difference between wet and dry. Good luck and happy growing 🌱🌱🌱
The bigger leaves drooping first is a sign of dryness.
As they have a much larger water content than the smaller leaves, they will droop first, before the smaller/newer leaves do, which will remain upright for longer.
Hope this helps, Organoman.