I've had some students who started at 50. The biggest problem is that it is hard to find a junior position as a 50 year old. Age discrimination is definitely a thing. If your goal is to make a career in programming from scratch, you might be too late, but 30 is sometimes already too late in that regard. Networking, nepotism and the good old "foot in the door" helps there. If your goal is just to learn and maybe apply it to your current job or your own business, than it's perfect to start now.

Most succesful students I've seen of the older category are those that have drive and passion. One student had her own fotography studio and wanted to build a database and website for that. She struggled a lot, but persevered and made a great application. Another was a taxi driver who's children put him in the course. He turned out to be very talented and made and excelllent application for planning taxi rides as his final project.

So it depends what your goals are.