With time and careful observation you will know when they need water and appox. how much. You've seen what they look like in a dehydrated wilt? So you now know the outer limit on watering time for that size container and you can expect the plant to take water at an increasing rate as it gets bigger.
Lift your pots after watering and feel the weight. Lift them when they look dry and feel the weight. There should be a noticeable difference if they are ready for more water. Get a water wand gauge and put it in the soil once a day. They aren't always gauged right so you can't trust the values but I find they work well on a relative scale.
If you let your soil get too dry and the plant wilts, there is a good chance you will have trouble wetting the soil again. Large dry patches that pull away from the container. When watered it just flows straight to the bottom and out. So good idea to put planter trays under each one and water from the bottom of the plant if this is a concern. Just pour your water in the tray and let the soil wick it up, expanding again.
To learn the amount to water, fill up something you can measure with and keep putting water on very slowly, taking some short breaks. When water starts to come out the bottom you then have very good idea of the amount to water for that size pot. If you are using synthetic nutrients, it is good to let some extra water run off every now and then to push salt build-up out of your soil.
Having good soil is really the key to easy watering. With a good mix you will have elements that hold water and elements that drain water. It is harder to over-water in good soil with proper drainage and you can get it to retain moisture longer at the same time, especially if you add an inch of mulch around the top of your dirt.