Hello Ritesh,

This question is very subjective. It varies on your current knowledge level and your ability to grasp the concepts. If your vocabulary and knowledge of English are decent enough, 6 months is enough to prepare for VARC.

However, please do note that VARC in CAT is quite different from normal English sections in other exams. It tests your vocabulary, reading ability and retention power along with the speed. So, the best way to find it out is to give mocks from the month of May. I would suggest you solve the previous year papers right now and check your performance. If it is decent, start giving the mocks and see how you are faring in them. Based on that plan your time table. 

Although you have mentioned here that you are a beginner in English, I have mentioned the plan chart for every aspirant which is a must to follow. Please do not consider yourself a beginner or weak in any section from now, else this mentality will keep on haunting you till the end. Have an open mind and prepare as per the above idea. Do let us know in case you face any other doubts or need any advice. All the best!