I'm in the awkward position of having only gotten a CS degree and taken programming seriously after 30, so I suppose I'm the worst of both worlds. Of course, I also started going gray at 30, so...
I just graduated with a CS degree at 36; have an offer and will start soon. The age aspect is scary, but I've honestly found it less of an issue than I thought. The most difficult part is pushing past the part of me that says I'm too old to be starting now.
I'm currently working as a developer and aiming to go back to school within the next year or two for physics, after some catch-up math courses.
Good for you for even setting out. It's intimidating, if not down-right frightening to start all over again at something.
But hell, the unconventional is increasingly becoming the conventional. Some of the best advice I ever received was from a doctor I had when I was young. He was an old Jamaican man who went from the slums of Kingston to Chemical Engineering in the US to a practicing MD (physician, general practitioner) in a small town in Canada. He just said (kind of what you'd expect from a Jamaican man): not to worry about anything.
Just do things, make messes, clean them up, do more things. You just might do some good in the process.
I graduated CS at the age of 27 and thought I'd be at a disadvantage starting out in the industry due to it. If anything the couple more years seems to have helped me out quite a bit as I found it made me more relatable to the more senior technical people and management.
In the modern dev shops now the soft skills you've developed in the additional years you've had before getting into development will give you quite an advantage since 99% of places aren't just heads down coding anymore.
Where I've found I have a disadvantage is in my non-work commitments and free time outside of work. The younger guys can spend their evenings and weekends working on side projects, going to hackathons or just learning something new, whereas I come home to the family and try to spend quality time with them, do my share of the work in the upkeep of the house, yard, etc.
We only get one shot at life so you're never too old for anything in terms of what you want to spend 40+ hours a week doing to finance your life.
After 30 is totally fine. I know several programmers who either switched to programming around 30, or had a long break from programming. Sure, you may be a junior developer while younger people may already be senior, but there's time to catch up, and with a bit of maturity, you may have a far better attitude than young cowboys who think they know everything.
In enterprise adults are often more useful because understanding, dilevery in schedule and the ability to do what you are told is immensely more valuable than doing things in a fiery passionate way on some new tech.
On top of that, while you might learn slower, you probably attended more classes and played less video games during them than 90% of the twenty year olds.
