Clay cant be too wet or too dry in order to compact. If too wet, the clay gets like a waterbed, push down in one area, and it lifts in another. Too dry, and it just crumbles.

When you get your clay dried enough, it should be moldable, but not with a lot of ease. Put it in the bucket, compact well to about 2" thick and fill with water. Mark your water level and cover with a lid. Keep the bottom of the bucket a little off the floor so if it leaks, water can drain. Let it sit for a few days and see if the water level dropped much.