It can take a month to year to fully cure soap. That is a big range. So, how can you tell when it is done. First, we must understand the difference between fully saponified and cured.
Saponification is the process of converting fat or oils into soap by treating with lye. With hot process you are forcing the soap to saponify quickly by introducing heat. With cold process it takes about 24 hours after you finish pouring the soap. The poured soap will remain heated and goes through “Gel Phase”. While after saponification is complete the lye is no longer a problem, and you (in theory) could use the soap, it will not be solid enough to withstand use. The water must evaporate out and the soap harden up so that the soap will last longer and be more gentle on the skin. In soft soaps like Castile curing can take up to a year.