Greetings of the day dear candidate,
Admissions into various colleges will start right after board exams of class 12th will end. Also, the admisisons for various different courses have some particular eligibity criteria. So, you should wait for atleast til June for admission procedure to start.
See, if you want to take admisisons on direct basis then you can simply visit the college and fill the form and pay the fees but for that you need your class 12th marksheet. So that is why you should wait till the examination is completed for class 12th.
I hope this information will help you.
Thank you and good luck:)