If you can get a pot of the same size and fill it with soil. Feel how heavy it is dry and then slowly water it until water comes out the drains. This is a full saturated weight now you can use to compare.

Alternatively stick your finger into the soil to test how moist it is (an inch or 2 down, careful not to hurt any roots). If it is dry water, if not let it go another day.

Basically let them dry out between waterings, it will do you far more harm to over-water than underwater seeing how you can easily compensate for under-watering with more water.. it isn't so easy to take water out