I think you have got a lot of time. You should start studying at least 3 hours daily in the beginning. Then on weekends you should study 8 to 12 hours. Follow this routine and if you can take leave for a month or two near your exam to revise and wrap up everything you have learned over the course of the year you will do just great.
Make sure not to collect many info about CSS from different people, a lot of views will confuse you. Start preparing compulsory and optional subjects, while work on your english on daily basis.

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Best of Luck.