I agree beaver, there is a general consensus in 20somethings that 'children arrive in your 30s' or '30s is best age to have children' because, these days, this is when most people tend to have them (cannot cite my source for that)
but if you feel ready- and you are committed to one another - and seem rather settled and happy - then .... why wait...
He does have a point, as I had my first when I was really rather young and I have to say that I, in essence, felt a huge sense of loss - of a whole side of my identity- because there are so many things you cannot do when you have a baby. So many enormous life changes. Yet I doubt anyone here would say they regretted having their children. It's just not an easy ride.
So, in a way, if you enjoy going out, and travel, then yes it is sensible to really make as much of it as you can because there is no going back once babies arrive. I found even a trip to the dentist, was like a holiday, because it was time out from a screamy baby. I sound bad but I don't think the downsides are talked about much. It was like 'me' had died and been replaced by a changed version, who really couldn't do a lot of things anymore. Even going away - try being on a plane with a baby. Try sitting by a pool, or having dinner. Not easy. BUT if you have the support there (I did not) then you could perhaps tell your DH yes but we can still do x, y, z. It's only right he might need some reassurance that his life is not going to be 'over'. o you have friends or family who could look after the baby so you two can still go out together, or can go away for a while together? Then his arguments hold less strength.