THIS MIGHT READ LIKE A WARNING BUT ITS NOT. i think a lot more talented people would stick with comedy if they knew that it's a grind and not a fairy tale, and i think this sub would be so much better if it weren't a constant stream of "i'm maybe gonna try comedy help me" and "here's my 2nd set ever thoughts?" i think comedy sucks, but i also love it, but that shit never gets said on here. can we just permalink a post at the top of the page with realistic advice for newbs and an announcement that videos of newb comics are banned? anyway, the question...
short answer: no. past the age of 15 you're never too young or too old to start comedy.
long answer: no, most people in this industry don't start breaking until they're a decade or so in, so the earlier you start the better. i don't know the city you're thinking of starting in, but i guess that doesn't really matter. the general experience when starting out is pretty much the same everywhere.
at 16 you should be ready to walk into a huge culture shock. the high school "you can achieve anything/you're special/make your own future" bullshit doesn't exist in stand-up (probably a nice head start on a fact of life your peers won't figure out til their mid 20's). the people (comics, duh, but also the door guys, bookers, club owners, etc.) will be unlike anyone you've ever encountered. comics are generally cynical, depressive, fiercely opinionated, highly articulate, loud, self-serving narcissists. comedy is a largely glamourless, isolated, lonely endeavor. at the same time, comics are some of the most fun, subversive, unique, and loyal people you'll ever meet, and comedy, when it's fun, gives you a self-actualized joy most people will never experience.
if you're into taking the plunge, by all means do, just be ready to a) deal with the majority of venues being 18/21+, figuring out how to talk your way in, not being upset when the won't, and not being a shithead that tries to order drinks when they do. b) catching a lot of ball-busting about your age from every comic, and getting swamped with a lot of unsolicited nonsense advice from the aging "never made it" comics. the ball-busting stings at first but it's actually affection. you'll learn how to dish it back, and it can actually help clue you in to how you/you're act are perceived. the advice stuff is a hard lesson you have to learn early in comedy. it's hard because it's usually well-intentioned, but it's also usually very dated and/or rooted in the insecurities and regrets of the person giving it. i've seen several new comics fizzle and fade getting caught up trying to heed every bit of guidance some regional off-night headliner with an appearance credit on season 2 of LCS doled out to them. especially at 16, you're going to catch a lot of this. take all of it, even the advice you ask for, with a grain of salt. you run the show. c) most important of all, know that comedy is a craft above all else. it takes years (decades even) of diligence, discipline, and belief in yourself to excel at. you'll fail, a lot. especially the first couple years. you'll get better, even really good, and it will still suck. this industry is 98% rejection which means you really have to find enough joy in the process to be prolific and push yourself forward. your perceived hardship is not unique. becoming a successful comic is a long, shitty grind for everyone. if you can handle that, jump in and don't look back, and if not then good on you.
TLDR: i typed it just read it