Starting doctorate at the age of 22?

That's not such a young age. Many students go right from an undergraduate degree to a graduate program.

You'll need to finish your undergrad degree first. The rest depends on your program. Many doctoral programs now integrate a master's degree into them, and it is possible to receive both degrees in 4-6 years (depending on how hard you work). I received my masters's and Ph.D. together in 4 years.

You need to earn a bachelors degree before you can start a graduate program, and the first few years of a doctorate program are the masters classes. You're about 6 years away from starting a PhD.

Degrees are completed one at a time, with an undergraduate degree usually being a prerequisite for starting graduate studies leading to advanced degrees.

You can't skip the master's degree.

Excel in your undergraduate studies and get admitted to a PhD program.
Generally you have to complete some research work before you are admitted to a doctoral program so speak with your professors about research possibilities.

Good luck - I am impressed that you are thinking so far ahead..

Once upon a time, 22 would have been a typical age to enter a doctoral program. It's still not "such a young age."