I've never moved mine very far to dry, but it seems to me it depends more on what kind of mold you are using. If its a metal cake pan or other heavy duty mold I'd say move it any time. If its one of those black plastic ones that are sold on line I doubt that you can lift it full of wet concrete and have it hold its shape. You could slide them on to a tarp one by one and drag them away. You do need to shake them and tamp to get out the air bubbles soon after pouring, so if you are using more sturdy molds you could pour 5 or 6 then tamp shake move.
Have fun and remember to post pics.
kathy

I use the black plastic molds....what I do if I am going to need to move it after I pour it I set the mold on a board. I use the board to bounce the mold a little bit to get the air bubbles out and if I need to move it I do it right away after pouring it by picking up the board and all. I would not move it if it has had much time to set up because the cement will crack apart and won't really ever get back together. This will make your stones crumble.

Thanks for the info! I was thinking about using a 9x12 cake pan (got to find a cheap one). I want to do a lot of stones so a very sturdy mold would be a good idea. So do I just fill the pan about half full so that my stones come out the right thickness? I want them thick enough so that they will hold up well.

The only stepping stones I've made so far are the rhubarb leaf ones. They have a piece of chicken wire imbedded and are a total of 2" thick. Have lasted thru several very cold winters with no problems. I wouldn't move a stepping stone for at least several days except carefully and supported by a board. We made ours on a piece of plywood and moved it so it was out of the way then left it.

I recommend lining a cakepan with plastic so the stone can be removed. Some people oil them but I haven't done that. When we did hypertufa pots we lined them with plastic and they were easy to remove.

There are many factors: type of mix, temperature, thickness, reinforcement, etc., but in general:

Concrete sets in two to three hours
Concrete reaches 25% of itÂs strength in 3 days.
Concrete reaches 50% of itÂs strength in 5 days.
Concrete reaches 75% of itÂs strength in 10 days.
Concrete reaches 90% of itÂs strength in 21 days.

dcarch