droopy leaves are usually either over watering or underwatering.
the more limp and lifeless the plant looks it is usually underwatering, the more droopy the leaves look its usually overwatering.
that being said, if you are in soil, if you dont water enough the first time air pockets can be left in the soil. a good amount of water (10% of the watering amount)coming out of the bottom of your pot is what you want every time you water. cannabis likes a wet dry cycle, meaning it likes water and then to dry out for a little bit, but once the leaves start to go limp you know you have waited to long to water and have stressed the plant (but they also droop from overwatering)
its a balance in between. You can get a soil probe to measure wetness, but they can damage your roots... Best is to gauge water by weigh of the entire plant and container. You will get better at judging this as you become more familiar with your containers and their wet/dry weights.
good luck, hope this helps