At what age is it optimal to stop weaning a child from a pacifier? We …

At what age is it optimal to stop weaning a child from a pacifier? We use it only for daytime naps, and mostly without it all the time. Yesterday we lost it somewhere, I think buying a new one or should we already start throwing it away? How then to put him to sleep during the day? I usually give him a pacifier and he understands that it's time to sleep.