Hi aspirant,

If you have the passion and the resources then "START RIGHT NOW" , why wait for college? There's no right time for learning things, If you start today you will be way ahead in your coding skills when you enroll in your college. As you must be aware that the Union Ministry also has made coding mandatory for primary students in the NEW EDUCATION POLICY 2020 , so why wait?
Start with the fundamentals of coding , it doesn't matter which language are you working on. Once you master one you can apply it in other languages.
Let me help you with some of the basics,
For website development you must learn HTML & JAVASCRIPT .
C ++ and JAVA for desktop application.
For mobile application JAVA for ANDROID and SWIFT for iOS.
Always keep learning and never be satisfied with your knowledge, at the time when you will join college you will be ahead of your classmates.

All the best!!