I'm 34 with 3 kids, with the first coming at 28. I wish that had started a few years earlier, say at 25.
You can't run away from the effects of age. Being a middle-aged parent of small children is not only exhausting, but it comes with the corollary that you may simultaneously be providing care for your own elderly parents.
It's straightforward enough to establish a solid career by age 25, while still allowing for some of the "finding yourself" time that people seem to crave.
On that subject, I feel like our generation has gone overboard in the pursuit of some nebulous "I'll know it when I experience it" idea of fulfillment, and that it has a bizarre rider that living a fulfilling life is somehow mutually exclusive from child rearing and that you start wearing mom jeans and khakis as soon as you have kids.
You can still go to shows, play sports, etc., you just have to balance it with your child-rearing responsibilities. And that shouldn't be a surprise or a burden to anyone who actually wants to have kids.
Now, if you don't like the idea of making compromises to raise kids, then don't have kids. Nobody cares either way if you do.
Just don't expect that you can "get it out of your system" before you have kids - you can't.
Once you have kids, you'll still want to travel. You'll still want to drink beer and watch hockey all night. You'll still want to get tattoos. You'll still want to go to a club to watch some hot new Pitchfork darling. You'll still want to hang out around a bonfire until 3 a.m.
Life doesn't suddenly become an episode of Up All Night. Unless you actually want it that way, which is also fine.