Interesting question. I don't know that I have wishes, exactly, but I can tell you what we did.
We had our daughter late-ish. I was 38, DW was 34. That was 1.5 years ago. DW and I met when I was 32. I spent my 20s living overseas and getting a MA degree, and she also has an MA degree. Personally, I tend to be pro spending your 20s doing whatever you want (traveling, pursuing some artistic / athletic profession, etc.) because I found it easier (like mentally) to be "settled" (and work 40 hours a week) in my 30s. And I agree that kids don't necessarily prevent travelling, but they absolutely change it. The way / extent that I traveled in Asia in my 20s (lots of bike camping, 24 hour bus rides, very skeezy hotels) is decidedly not family friendly.
That said, there are absolutely positives to starting earlier. I was much better at sleepless nights in my 20s. Plus, DW and I are almost certainly just going to have one (although, to be fair, that decision wasn't based primarily on our ages). If you want to have multiples, younger might be better. I also love what was said about knowing your children and descendants longer. I agree with that, but at the same time it isn't really a regret because, before my daughter was born, I wasn't missing her.
One thing that was helpful for us, too, was building (well, finding) a support group of like minded people -- for us, this was a Buddhist group. In addition to the meditation / spiritual aspects, it has been great having a network of folks who have similar attitudes towards materialism, media consumption / screen time, food, etc. Makes us feel like we're not aliens. :)