It depends on your recipe and if it gelled or not. When you press on it and gives a little but is firm you should be good to go. Cutting when top hard or too soft can pose issues like crumbling. There are May topics on the forum regarding this as it’s frequently asked.
Depends on your recipe & your process. As soon as it is set up enough to remove from the mold, I let it sit out to rest a few minutes or hours (as I said, it depends on the formula and your process.) Are you talking about CP or HP soap? Did it go into the mold very fluid or very thick? Did the soap heat up fast? Did it gel or not gel? What kind of mold are you using?
Did you use a low or high or mid-range lye concentration or water to lye ratio? (That's part of your formula, by the way.)
All these things impact the correct answer.
With a gloved finger, check to see if it feels like pressing on a block of cheddar cheese. If so, it is good to cut.
Some examples: A 100% Coconut oil soap can be ready to cut in a couple of hours. A 100% plain olive oil soap (not pomace) can take as long as a week to set up sufficiently to unmold and cut.
Usually, i like to wait until my soap has cooled, its firm to the touch, and when i peel the sides of the mold, it doesnt rip. Usually i am in bed by then, so i unmold/cut 16-20 hours later depending on when my soap was made. But over half my recipie is hard oils, so it hardens up fairly quickly.
I made a soap this morning around 9:00 and i used lavender and sage FO from NS, and oddly enough, it extremely slowed down my trace. I checked on it a moment ago, and it is definitley not hard enough. I can press a little, but just a tad too much you can see the indent and my fingerprint. So i will wait for late night/morning to cut it