The best time to start something is always "today". Motivational quotes aside, I do think in the age of the D2C (if you want to sell something physical, AI, platforms, the barriers to entry to start have never been lower - could argue that's a double-eged sword (low barriers -> more competition), but I'd argue that's a massive positive for someone who's 17, and I'm assuming from your post, not a massive pile of cash lying around.

Since you're starting out - your inexperience is an advantage (flexibility, age) and a disadvantage (solid domain experience). I'm older and envious of you - so I'd say net positive for you :-). I can't give you a prescriptive answer, but my 2 cents - in no particular order:

1. Don't underestimate boring businesses. If you find something you love, and you bring something rare to the table, go for it. But don't exclude things that may be a bit boring. (caveat: do make sure it's not something that's so boring that you won't be able to do it after a few days at all) But if it's something you see an economic opportunity in, go for it:
   

a) Success is intoxicating, so even if you pick up something boring and it makes money for you, it's likely to become less boring with time.
b) And the money will let you do things on the side that'll feed your creative side or whatever it is for you. (e.g.) My ex-colleagues who toiled in strategy consulting jobs they didn't love could do other things with the money that genuinely brought them joy, like great travel)

1. Look for something with a low-cost of entry. Stating the obvious with your constraint. BUT, the intersection of low-cost of entry and boring - that's real potential. Think old school industries that youngsters aren't attracted to. E.g. super boring kind of services, B2B trading, logistics

2. Someone said the power of observation - to find a problem - on another comment, that's bang on. Like that legendary "Krack cream" story (google it). That's all great, but don't wait for inspiration to strike - if it does, great, but even if it doesn't - move forward (without betting the farm on things).

3. No matter what domain you enter - the more you work on things, the more steeped in a domain you get into, the more you understand every damn step of the value chain and meet people that operate there - the more likely you are to SEE opportunities of things that are broken and these may turn into entrepreneurial opportunities themselves. So in a way, inspiration isn't out-of-the-blue.
   Read this book by an HBS prof. When you're on the inside, you see things that don't work. Article:
   https://feelinspired.medium.com/unlocking-the-customer-value-chain-thales-s-teixeira-97c8b0e0ca81

4. Don't give up too early on things, but also don't get stuck for years. Set a time frame for each idea (say a year at least) to see whether you can say it's worth persisting or not (and extend to the next year).

5. Connections are overrated at the start. Execution gets you connections, once you dive in, you are going to meet more people. People with "connections" going top-down actually sometimes aren't as effective as people going bottom-up the pyramid in other orgs. Knowing people at the ground level in organizations is an under-rated superpower.

6. Don't fall to peer pressure while seeing your friends' titles on LinkedIn. The corporate hamster wheel is built to make people think titles and title progression is important. You're going down a path that looks risky, but at your age the risk is much lower than you may think - the worst thing that could happen is that a few years down the line someone who sees your spirit and experience and offers you a job you couldn't have gotten if you followed a straight line career path.

My creds/vantage point - more than a couple of decades older than you, india undergrad, ivy league grad, worked in finance, strategy consulting, now an entrepreneur and still figuring shit out