Hi, Year 5 is the right time to start preparing.
My daugher sat the test last year and passed.
The books we were recommended to practise with is the Bond assessment Papers.
We didn't time how quickly she did the tests until the July, August just before she took the test in Year 6.
She would benefit in reading as many classical books as she can, keep a dictionary handy when reading and look up any unfamilar words.
Learn all the times tables and focus on Verbal Reasoning as primary schools dont teach VR. My daugher was strong with VR, English good, weakness in Maths, luckily the Maths Paper last year was easier than normal, but they made the English hard.
She studied so hard, even the night before the test! She was quite lucky as the night before the test, she sat a Maths paper and was stuck on one particular question. My husband helped her out and showed her how to do this hard sum.
Luckily for her this question showed up in the exam! She was very pleased, so even studying the night can help.
On the last page of the English paper they normally have a question worth 12 points, so make sure she knows if she is stuck on 2 questions, then dont bother wasting time on the question that is only worth 1 point, when she could be answering the other one which is worth loads of points.
I hope it goes well for you and your daughter, fingers crossed.