You probably know that wine, if kept in optimal conditions, is better to be aged for a number of years, well this is the case with soap as well. Soap needs at least 6 weeks to dry( in the soap world that is called cure) but is way better when it’s even older. For example, olive oil soap(soap made only of olive oil as a fatty acid) will benefit from one year of curing(drying). That may seem like a long time to wait until you can use your soap, but believe me, it’s all worth the wait. A soap that has cured for long enough lost more water, it becomes harder and will last way longer in comparison with a ”freshly made”(6 weeks old soap bar). All this curing will make a natural soap bar more cost-effective, wasting less down the drain with each wash. Depending on the recipe a solid soap should have around 12% water. Our soap bars weigh 100 grams when initially cut, but a month in the curing process they can be less than 90 grams.
There are, however, bad sides of the curing process, Essential Oils tend to evaporate in time making, leaving the bars with a simple smell of natural soap. Depending on what is important for you there are options to consider. If having a lovely smelling soap important then use it as soon and you buy it. If having a long-lasting soap is important then put it in the linen cupboard, or between your clothes and use it later on.