@Applesandpears58 when you say the nursery has started towards an EHCP, has an EHCNA request actually been submitted to the LA? If not, you should make the request yourself ASAP. On their website, ISPEA has a model letter you can use. If a request has been submitted, what week are you on?
Delaying DS starting by 6 months would need careful thought. It is possible you won’t have an EHCP by then, so he would then start in reception in mainstream but having missed the first 6 months of transitioning into reception. Would DS's nursery allow him to stay on? Are his needs currently being met? There’s the option of sending him part-time too.
Because DS is summer born, you could request to defer, so he starts reception in Sept 2026. However, without an EHCP, you would need to school’s admission authority to agree to being educated outside of DS’s chronological year group. This would also need careful thought. Because of how long even expedited appeals are taking at the moment, you may not have a good EHCP by September 2026 if you haven’t to appeal each stage. Deferring won’t solve your issues, but it will allow you time to secure a watertight EHCP when there may not be time for a 2025 start.
If DS is to start reception in Sept 2025 or at any point in that academic year, you should make an application for a place via the normal admissions procedure because you won’t have a finalised EHCP by the application deadline. If an EHCP is later finalised, the school named in there with override any place offered via the normal admission arrangements. In line with the government’s handling admission requests for summer born children guidance, even if you want to defer DS to be educated outside his chronological year group, most (?all) areas require you to apply in the normal age group as well.
Do you have any specialist early years assessment places in your area for DC who are going or need to go through the EHCNA process?