I have young kids mid 50s. it's tough, but keeps me young, active and I believe more enjoyable as a person (not that I'm much of that lol).

I've spent all my 20s coding and learning and actively decided against relationship, as that would have completely eaten my time and I wouldn't enjoy how that time was spent.

If I could choose an age to start having kids, it would be 33. Still enough appetite for other stuff, but also a good amount of desire to procreate.