It really depends on the nursery , so I would call and ask them when’s best. Some in my area have waiting lists , my daughter (2020) when she started we applied about a month before and was told she literally could of started the next week as they had space ( but we hadn’t moved to the area yet)
The one I’m looking at said for me to apply when he’s a year and a half so I’ll be looking soon! My neighbour works for them which is good though 😂
My son is in nursery already two days a week then increases days next year x
I would honestly enquire now tbh. Especially if it's a nursery that takes younger children as the children they've already got will take the preschool places. If it's a school nursery place you'll have more time, but no harm in asking when applications open for 2026 so you're prepared.