Reading all these comments I just keep thinking it's all a matter of priorities. If you really want to do something, the sooner you do it the better. Responsibly, of course.
What "responsibly" means in any case might also be influenced by your priorities. For instance, a lot of people say "We're not financially ready to have kids" but they really mean "We can't keep up the fancy holiday trips if we add a kid". If your priority is to have a family, you might cut on holidays and have the kid.
That applies to some, even plenty, of cases, but I acknowledge that not for all. At least where I'm from, it often feels everything is set up to make it difficult for people to build a family.