Let's not lie to ourselves: kids are demanding. There are moments when I hate my life (usually when I'm falling behind on work, errands and sleep, simultaneously). But then, one minute I'm feeling sorry for myself, and the next minute my daughter does something silly or touching, and I suddenly feel like the happiest, luckiest man on the planet.
Looking back, I'd say the perfect time for a kid is the earliest moment when you feel you have control over your life and yourself. I.e. if you know you're struggling with personality/emotional/mental problems, try to sort this out first. Other than that, it's better to have them early, when you're still full of energy: it'll make confronting the challenges easier, and leave you more energy to enjoy the rewards :).
But it's still true: all time management problems look serious until you have your first kid. This will teach you about prioritizing real quick - but also will shift your priorities, so it doesn't hurt as much as it sounds. For example, before becoming a parent, I was worrying I'd be depressed over not having time for my side projects. And indeed, I have almost no time for them[0]. But I also feel much less need for them. The desire for independent creative expression is still there, but the daily challenges of parenthood often tickle similar areas of the brain - the kind of how artificial sweetener can substitute for sugar without being the real thing (and also makes you feel better).
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[0] - I'm hoping that when my daughter is old enough to communicate verbally and reliably keep attention on a single thing for more than 30 seconds, I can get her involved in helping me with tinkering in stuff. But that's still years away.
Cheers and good luck when the time comes :)
Be excited, and don't worry about the tradeoffs. For me, they weren't tradeoffs at all given the magnitude of the reward.
I'm excited to have kids, even in spite of the tradeoff involved in my spare time.
I don't need endless reminders of the tradeoff. That's just piling on.