The earlier, the better. Study abroad preparations can be time-consuming, as significant research will have to be done on each country’s offerings, along with finalising the monetary aspects of your international education. A head-start of a year will give you enough time to think over key areas, such as the subjects you wish to pursue, the features of the course in question, career options and life post-graduation, however if you’re not a native English speaker, you may need more time to attend classes and fine-tune your language skills to the expected standard.
Planning done within a limited timeline of 6 months or so may not be advisable and may lead to you making hasty decisions concerning the next three or four years of your life. The application process itself may have set deadlines and dated requirements which you should adhere to: the bank may need you to show proof of financial stability, which will require a set amount of funds shown to be present in your account in the 6 months leading up to your visa application date.