It depends on so many things like future health and personality that it's impossible to predict. But I'd go for it sooner rather than later, if you're going to do it at all.
My Dad was 50 when I was born, and my experience was very much like the poster above whose father was an "old man" by the time she was a teenager. He was of a generation of men (I'm 44 now) who weren't that hands-on with their kids anyway, and was thoroughly set in his ways by the time I came along. He did a few things with me (bike rides, fishing) but more in a grandfatherly sort of way, and based around his interests rather than mine. His health declined in his 60s and he found even my mild teenage rebellions very difficult, especially as his attitudes to discipline had an extra generation gap and he expected his word to be law. I was then worrying about him, potential need for care, etc. at the same time as dd1 was tiny (as I do now, for my Mum, who was in her 40s when I arrived, while they are early/nearly teens). He died at 80 when I was expecting dd2.
So not a wholly positive experience, but some of those (like the discipline thing) aren't likely to apply to your dh. Nobody can predict their health, but statistically the older you are the more likely health problems are. It's important to think about the future as well - not just energy for a baby/toddler, but the future with teens and beyond. I've heard great reports of older fathers who maybe worked hard in their younger years but are ready to take time to appreciate a child and have much more patience.
To show how individual it is - Portofino's post struck a chord, with her dh who wants to potter pleasantly at weekends, and where nothing would ever be arranged if she didn't do it. My dh (43) is like that now, and he became a Dad in his 20s!