Goodness, why aren’t you thanking your lucky stars that she’s September born!? I’ve no idea why you’d ever conceive of sending her early and missing a whole year of her early years development.
Look at all the evidence around being summer born/youngest in the class- the outcomes/risks are really poor and follow a child throughout their education, the disadvantage is real.
People fight so hard to ensure their summer born doesn’t face these issues by delaying their start so would find your decision to force this on your child out of choice really mind boggling.
The only way I’d even be considering this is if my child was so exceptionally gifted - Ie can she read fluently already? But Is she very socially and emotionally skilled because that side of things is arguably even more important for navigating school and a skill one benefits from developing over time. Even then, I’m not sure why you’d take the advantage away from her and risk knocking her confidence ?
My 2 year old is super bright and ‘school ready’ now based on the fact she can dress/eat independently, write her name, is sociable and confident etc. She truly seems on a level with some of the (younger) kids reception but would I send her to school now!? Of course I wouldn’t!
as a September born Who did very well at school I was put up a year a couple of times at primary as I was performing far ahead of my year group (but also ahead of the year above too) and yet socially I was miserable and was desperate to be returned to my cohort.
Id do a bit more reading about the impact of starting school at just turned 4 if I were you and see if you can find any evidence to suggest it’s in her interests (I have researched this area extensively and the evidence is overwhelmingly in favour of starting as late as possible, the U.K. starts children at school much much younger than most other countries and this is for funding / economic reasons and not because of what would be in children’s best interests )