I think in reality it tends to be when they are a few weeks old, say 6 weeks.
By this time, you have probably recovered from the birth, hopefully bfing if you are doing that is getting established, you are confident feeding in public and you are emerging from the initial fog of the first few weeks when you don't know if you are coming or going.
By 6 weeks as well a baby has already moved on from being newborn - they can see and hear much better, start looking around, and smiling at you and waving their little hands.
If your baby is a very clingy one who won't be put down at first like my DD was, this usually improves by 6 to 8 weeks.
FWIW with my NCT ladies I think the first thing we all did was start meeting for coffees at someone's house once a week when the babies were all v small Then we all did baby cinema, and then at about 8 weeks or so people started signing up for classes.