I am in New Zealand and yes it is odd. We start school the day after our fifth birthday irrespective of when it is in the year.
If your birthday is before a certain date (in my sons school April 1) you go straight into year 1 (hence k equiv) then into year 2 (1st g equiv) the following year. If your birthday falls after that date you go in to a year 0 class for the rest of that year then in to year 1 the following year. So some kids going into y2 (1g equiv) will be amost a year older than my son born 30/3).
I put the grade equivalents because that is what is familiar to most people on the boards.
ah, makes sense. It's just like if we had a cut off on October 1 (we have ours Sept 1)
good luck with the assessments!