I think I'd start with 2 males, 2 females, all around 14-16. Girls won't be nursing, because that's 2 mouths to feed and, in the absence of anything from LDW to the contrary, not contributing to the gaining of tech points or buildings or food.

2 of each so if something should happen and someone dies, I've still got at least one of each gender.

1 very, very young child, who can go for quite a few years gathering collectibles while the others work, and just getting towards working age when I'm ready for the others to start having children.

That's getting the maximum value from my villagers while resources are scarce, and when resources aren't so scarce anymore, start building up the tribe a little