New s/o meeting your kids

I had a nasty breakup with my only child’s father. Days after leaving him, he made multiple dating profiles and was looking for hook ups to “get over me”. Started having girls come over to his house and introducing them to our daughter. He started dating a girl and they were taking the kids out together after two weeks of meeting. I was to blame because “how was he supposed to meet anybody when he has our daughter 24/7”. I’ve been talking to a guy for 5 months and we just made things official between us. He met my daughter today for the first time. My question is, when do you think is an appropriate time for new significant others to meet your children? Our child is 6 btw.