Define "dry".
Dry enough to walk around on? Immediate. People can walk on the carpet just the way you are when you're cleaning it without doing any harm.
Dry enough to not feel any moisture? One hour describes it best. But it depends upon how soiled the carpet was, since you will use a little more cleaner where there is more ssoil. I do, anyway. Then it depends upon how much air circulation there is; what is the humidity level. Also: did you finish up with dry pads? I don't normally do this, but if I think that I have wetted the carpet more than usual, I might do it.
hi Derek, I've found 2 hours with minimal moisture is a good rule of thumb. I have had to use more moisture when carpets are real dirty, then I dry pad after and still advise under 2 hours as a dry time. Never had any complaint or disagreement from customers yet.