When you water the plants. Give them a good watering; then lift the pot and get a feel of the weight. Water weighs 8 lbs (3.6 kilos) per gallon. That gives you an idea of how heavy your container will be. After a day or two check the moisture by sticking your index finger up to the 2nd joint. Some people say the first finger joint, but MJ plants like a good dry out between watering. I think the 2nd joint works better for my girls. If the soil feels moist and a cool feeling on your finger then wait a day. Also pick up the container and see how much lighter it is. If the container is easy to pick up; feels very light and there is no moisture/coolness to the finger. Then give it a good watering. After awhile you'll just be able to pick up the container and know when to water.
MJ roots seek out moisture. The top two inches may be dry, but the bottom of the soil may be saturated. Let the containers dry out a bit will force the MJ roots to search out the remaining moisture. Autoflower's tap roots drive down in the soil to help anchor it. Let the tap root search for moisture.
I use a moisture probe. I check the moisture on the second day after watering. If the moisture is in the moist/wet area I'll wait a day. I do not water until the container is very light in weight and the moisture is in the dry area.
I'll water my girls with 1/2 gallon of water (4 lbs) with a 20% run off. The girls will take three to four days to drink that 1/2 gallon of water.
Right now my Bubbles are in the third week of flower and they are drinking a bit more. I'll water them on the third day now; instead of the fourth day.
Sum up; Let container dry out; lift container and see how it feels dry. Give the girls a good watering with a 10%-20% run off. Lift the container and see how heavy it is. Then when the container drys out you'll get a feel of when to water. Remember MJ plants are very hardy and they can go into a dry cycle without really any harm. Just don't over do it in watering and dry periods. The MJ plants will tell you what they need.
MJ plants do not like a lot of water.