hi
we work at an overall 1:5 and this seems to work (i am over and above this and way)
we do have a higher proportion of over 3's anyway, with only a few being under 3 and for no more than 3 months as we start at 2y9m.
it can be hard to work out on a weekly basis.
how about classing those that turn 3 during a term not officially 3 till the next break (be it half term or the hoilday, maybe the eye grant terms?)
this might help out with staffing and make it more consistent?

ie
if a child is 3 in feb "class" them as not 3 until easter, then class them as 3
dont know if this will work?
hope that this makes sence