Throughout my life, I've held between 15-20 jobs and embarked on three different careers. My advice to you is to focus on what truly brings you joy and fulfillment. Seek out individuals who are thriving in that area and engage them in conversations about their journey. Don't stress over your initial jobs. These early experiences are valuable, providing life lessons that will reveal more about yourself and guide you towards your ultimate career - one that you'll pursue out of sheer fulfillment. Instead of obsessing over the end goal, embrace the thrilling adventure that leads you there.
I agree with Alex that a job pays the bills, at least that's the goal. Unfortunately, not all jobs can do that well, and it's hard to know which jobs pay better than others – so you need to ask people, and hope that they'll answer you (it's ok if they aren't comfortable, but worth a try). Something you need to consider when looking for a job is what's your priority: having good pay? doing something you're passionate about? do you want a standard 9-to-5 desk job, or do you want to be on your feet? do you want work-life flexibility at work, or are you ok dedicating yourself fully to your job? are you looking for mentorship and growth? do you want stability or risk? do you have contacts somewhere who can help you get into a certain company?
Stay curious, ask people questions, such as what interests them and how they got to where they are. I don't believe there is ONE thing you want to be. There is no way to know where life will take you, so I think of what I want to be FOR NOW and I stay open to opportunities – or I look for them by talking to people, researching companies and what they do, and reaching out to contacts listed on company websites or through my network (which you build over time). I found my first job by talking to A LOT of people – I had no idea what I wanted to do – and then asking the company if they could hire me after an internship. Never be afraid to ask for what you want.
Hope this helps!
My perspective that I want to convey is that everyone is different.
I'm the kind of person that keeps doing what I'm doing and stays at my particular company "forever" or until some life event happens that requires me to change. Basically I avoid change. Don't get me wrong - I'm there every day to learn new skills and help people and build up a reputation for myself at the company - I just do it "quietly". I'm not trying to impress anyone, it's a means to pay the bills, and if I like what I'm doing, even better.
On the other end of the spectrum are people that can't sit still. They either get bored quickly and want something different all the time, or just can't handle routine and incremental improvement. If you grow up in a dysfunctional family, that's a reality. You might get incredibly inspired to do something, and commit 100% to it for a short time, then be completely done with it. It just adds to your experiences and your life story.
Then there's the middle ground, I hear most people will change jobs up to 12 times in their lifetime and stay at each for up to 4 years on average.
To answer your question... there is no magical age for when you know what you want to be. You just have to be curious and try things - but also give it your best, don't be lazy about it - and it'll come to you. Either "it's a winner, stay" or "not feeling productive, next".