How did it work out for you? I am curious as I am thinking of shifting from fin. applied math (econometrics) to SE ...
I turned to software engineering because computer graphics gave and give me such a huge kick. I don't know what intrinsically motivates you so I cannot comment whether I would suggest the career for you or not. Here's the rub: software engineering can be viewed in some circles as blue-collar work, which means the work environments can vary quite a lot. Also, the discipline is really young, and it shows in the amount of cargo cult and bullshit quotes one finds peddled as "best practices". There can be gigs where co-workers are experts and those can be great, however, there can be lot of environments where co-workers are perpetual expert beginners and those can suck big-time (or so I've heard).
Realistically, software engineering is still a pretty solid career choice so from a sustenance point of view I'm sure there are far worse options one can choose.
The time limit is not age but how much experience one has doing software engineering projects. One needs several unders ones belt, preferably some that have actually shipped so that one sees what the end user implications of the said products are. How long this will take? A couple of years? Hard to say.