Yes, that is early, and now seems a reasonable time to start. Was wondering about the OP's dd.
I would set up and agree a time-table of study
Tbh, you can set up and agree whatever you like, it doesn't make much difference if the child hasn't agreed too!
Are these end of year exams going to actually mean anything? Affect sets, etc? In my dc's cases, they didn't. (They were only setted for maths, and at that stage didn't need to revise for it to do well.) If not, I can't see the point in getting too worked up about them. If the only casualty of a bad mark is going to be your parental pride, then your child is going to have to find their own motivation - and it might take getting a bad mark to spur them on next year.
Yes, *ask* your child what the exam will cover, whether they think they know it all, what they might plan to do if they don't know it, do they even know how to revise, etc. But you can't make them do it, and seriously, if they don't do much preparation, and they don't do brilliantly well, then that's a great learning point.