Well, no, not necessarily. If you want to sell it, yes. You must let it cure. The soap will be much better after curing. It'll be less drying, have better lather, and the bar will be more firm. I do CPOP, and I use mine the next day when I cut it. Just do the tongue test, and as long as it doesn't zap you, I'd say go for it. I'm impatient too, and there's no way I could wait to use my soap. If you're doing plain ole CP, I'd say wait 4 days, then try it. I think a lot of soapers are impatient, so we're not alone. There was recently a thread about this at the soap dish: http://www.soapdishforum.com/forum/index.php?showtopic=28567