Hey!
First of all I would like to appreciate your thoughts as nobody makes this move so early. So you're already ahead of many by thinking about this.
What I would suggest is start preparing for prelims first along with your graduation subjects. Like you could devote 2 hours daily for prelims after you come back from college. Gradually you'll develop a habit of taking out more time for this study while you manage your college subjects. Also devote 1 hour religiously for current affairs. This you can do anytime. Like while you're travelling to your college, you could bullet the points from the headlines and later on learn more on it. Listen, IAS isn't a joke. If you really want to be an IAS then do not let your focus divert. Because nobody other than you yourself can make you an IAS.
So Good luck.
Study hard!
Do let me know what do you think upon this answer. I'll be happy to help you ahead too.

Hello Priyansh.

 I would suggest you to first complete your graduation and then go for IAS since the minimum eligibility for IAS is 21 years. Till the time you complete your graduation you will be eligible to give the papers. If yet you are persistent on carrying on with IAS, I would suggest that you start your coaching from your third year itself since the burden is less and you get ample time to focus on your aim.

Hope this was helpful.

Good luck.