dear student

CPT is organised twice in a year- June and December. You shall register for June 2018. For this uh can apply online on Icai Site The Institute of Chartered Accountants of India

Eligibility is you must be pass in 12th. Having Maths is not necessary. But in CA you will have Maths in Quantitative Aptitude.

You can register for June Attempt till April.

And for now, focus on your 12. Gibe more time to Maths and Economics and Accountancy as it is there in ur CA Foundation Syllabus too.

hope this helps

All the best!!!