1. Is there one "right" time to start?
No. Different families and tutors give different answers. What most agree on is this: think of Years 3 and 4 as skills-building, and Year 5 as when skills turn into exam-style practice and timed tests.
A common rule of thumb is to aim for at least 12–18 months of structured preparation before the test (which is usually in September of Year 6). So if you want a calm, steady run-up rather than a last-minute sprint, that points to starting no later than the beginning of Year 5—and many families start in Year 4.
In very competitive areas, some tutors say starting in Year 5 can feel "late"; in others, a focused Year 5 is enough. Your child's current level, whether the exam includes verbal and non-verbal reasoning (which aren't on the national curriculum and take time to learn), and how much time you can give each week all matter when choosing your start date.