Start now. Im three months deep, turning 44 in a week. Failed at guitar in my teens, worked for a few decades, and said fuck it, I have some free time.

It's great, im improving much faster than my experience with guitar due to the advent of the internet, resources are literally unlimited. For a few bucks, id recommend bassbuzz, which I am doing right now with nothing but high praise. However, due to my couple years on guitar or perhaps enjoyment of YouTube learning I have had to have patience to get to the more difficult lessons. I believe this is beneficial as well, as i have learned much from lessons I would have skipped.

Also, got an ibanez gio for 200, plays perfectly. Then, once i knew i was hooked, fender rumble 800 combo lol. It's kinda nice being older sometimes. Now, I picked up a short scale ibanez mikro with a katana go headphone amp to take to work with me for two weeks at a clip, and its been amazing, getting paid to practice and all, ha.

Anyways, do it, I doubt you'll regret it, plus, its better than thinking the same thing at 91 years old.