I think not crumbly dry, but definately not freshly watered...when the soil is the same kind of texture it probably came out of the bag it was in originally to be honest is the best. Compress the sides, then put your hand over the small pot with the stem between your middle and ring finger (keeps any loose soil from falling, I assume your transplanting from a small pot into a big one, right?), turn it upside down and just slip the pot off the soil. It should all stay together, I always gently "loosen up" the rootball before I replant too.
I had a semi rootbound plant that I transplanted a few days before flower without loosening up the root ball. Yields were poor and when I checked the roots after harvest (10ish weeks later) they hadnt spread much into the soil in the new pot very much, this is why I always do this to the rootball, if you do it gently without snapping many roots you wont stress your plant noticebly either.
Hope this helps.
EDIT: When you learn to know how much water your plants need from experience, just start your plants in large pots btw. I generally start seeds in a 10L pot (think about 2.5 gal), you just have to water them daily at first, but quite selectivly.