Generally speaking, couples who date a year or longer have a stronger relationship when they marry. This is also true for single parents but keep in mind just because the couple is ready doesn’t mean the family is. You can have a high quality couple relationship but not know how you are going to merge your families. Take time to date thoroughly and bring the kids along in the process. This may take months but better to take it slow and progress as a group than move fast and fracture your family.