I am new to stamping also, my last batch of soap that I stamped turned out pretty good, I am thinking that earlier is better. I took it out of the mold, and cut & stamped the next day after making it. I used a mallet and gave a couple of firm taps-not to hard, not to soft. Worked great, didn't mash up the tops of my soap, etc. Like they say practice makes perfect, lol. HTH.