As others have said, it is not compulsory and in some cases is not beneficial. I pulled my son out of 4yo kinder due to the lack of structure and guidance (lots of free play then lots of telling him off for not playing the "correct" games, but no telling him what they were) and he has coped perfectly with full time schooling. I have found childcare to be more beneficial as school preparation despite not having a teacher as such. Basically what I'm saying is that if she is happy and learning where she is, and kinder hours are going to be a struggle, then consider if it will really be worth your time and money or if more time with you would be more beneficial.

It's also important to note that schooling of some sort is compulsory from 6, but that this can include home schooling or unschooling at home.