Took me a while, but that's because I started with really bad quality and lacked experience. You could also reach that goal faster if you collaborate with other YouTubers around that sub count. It really depends on how much effort you put in and how your videos get around the community. If you make the best content possible, but no one watches it, then you are out of luck. So I would say it's a mixture of making good content and advertising yourself correctly. Avoid sub for sub as well. In the end, it's not going to help you. Best of luck!