If you've got the choice... I'd say 3.
Given the August birthday, I would comfortably say from the start of the year she turns three. If you put your name down now at some of the good centres in your area, you'd probably get in. PM me if you want some names.
But the next year would be OK too. That would be 3 year old kinder year, right? (Maths SO not my thing.)