I started early March and revised a little bit each day, starting with the sciences first as I had the most amount of exams in this, and then built up other subjects recently. But to be honest, there's some subjects I haven't revised at all, simply because I'm happy with the grade I'm getting in them and either because every single lesson since January has been revision or because I just know the spec well enough I haven't forgotten it.. I don't know anyone else who started as early as me, most I know started early May and are revising each exam as it comes.
Most of my revision notes and materials had all been made up in preparation for previous mocks.
Like sophie-xx said, revision in year 10 will not benefit you unless you're revising for mock exams, in which case, revision then is a good time to trial different revision methods to find the best one for you. Or if you're sitting any exams early, then revise for those. Seriously, you should use year 10 to focus on coursework and classwork and mocks. You shouldn't even think about your main exams until after Christmas in year 11. It'll stress you out early and by the time exams come, you'll be sick of the materials you have to learn and probably discourage you from continuing at such a key moment.