meeting the kids

How long after starting dating someone should you wait to introduce them to your child/meet their child? Things have been getting really serious between my boyfriend and I. I would love to introduce him to my daughter (she will be 5 in September) and he wants me to meet his daughter (she will be 6 in August) but don't want to do it too soon. We also don't want to wait to long either since we have been talking about moving in together in a few months. Just looking for advice from people that have went through this.