Parental engagement and "nudging" the child to do homework, keep up, etc is vital in my opinion, not necessarily "hot housing" with extra work etc.
Our philosophy with our DS was to keep him just ahead of the curve so to speak. So he could read and write, and knew his numbers, before starting school, but no more than the basics, i.e. reading a Thomas the Tank engine book rather than Shakespeare. Counting cars on the road side rather than equations, etc.
If he came home with homework, i.e. a page of sums or some spellings to learn, we sat with him to ensure he did it. If he said he was struggling with something new, we'd sit with him and go through it again, until he understood it more.
All so that when he was in the classroom, he could benefit from what was being taught, rather than sat their twiddling his thumbs waiting for help to come, or getting demoralised that he didn't understand something.
Not doing a homework, whether primary or secondary, whether academic or arty, was simply not an option. We stayed on top of his homework obligations, by checking his book bag, then homework diary and then show my homework app. It was just his normal routine that he knew he had to do his homework before evening "fun time". That early years good habit stayed with him right up to his A levels!
When you start getting behind is when problems arise. You lose the impetus, get demoralised and disenfranchised, etc. Little and often really is the answer to keep slightly ahead of the curve and be ready and in a position to learn in the classroom.