I’m all for it – my daughter (year 9) is sitting 5 this year.
Obviously all the schools differ but I’m very pleased that some can get them to GCSE standard in some subject so quickly. It does give them the time to gain more experience on the subjects they’ve picked for their options and in a lot of cases it allows them to start running AS level along side the GCSE level.
Staggering them like this also gives them the chance to do their best, they can resit (but only once as far as I’m aware, then you have to pay).
If the child is able and emotionally ready to cope with the exams at this age then go for it.
I’d have loved to have spread mine out over a couple of years rather than have a 2 week cramming hell…I’m sure I’d have done much, much better.