As some already mentioned, it's never too late.
I'll add a little bit from my experience, of having started a technology company in my 20s and then, later, starting two others after my 40s, all of them active until now.
The two most important things I felt different were: time and energy.
I explain.
The time I had to work for my startup when in my 20s was huge, almost any time I wanted, and everyday. And that's what I did. I worked everyday, all the time. When you love the company you founded, that's what you want to do.
But now, after my 40s, life changed. Married, children, and a lot of obligations and responsabilities. I definitely don't have the time I had in my 20s to dedicate to the startup. And yes, you need to dedicate time!
Regarding the energy, I mean the energy related to health, physical capacity, intellectual concentration and ability to handle stress. These are all different 20 years down the road. And I amazed now, to see and feel the amount of energy one needs to dedicate to the startup. I had forgotten this.
I'm not commenting all other aspects related to loving what you want to do, entrepreneurship capacity and persistence because I'm taking these as given.
So, in short, if you have the _time_ and the _energy_, go ahead do your startup. Otherwise, go do something else.