ESF kinder to ESF primary

My son will be studying Victoria PN this year. If my plan is to send him to ESF primary school, should I apply ESF kinder I know it's not guaranteed. But what's the percentage of ESF kinder students can get into its primary schools? As Victoria has primary school also, I am struggling if I should let him stay at Victoria for K1-3 so at least have VSA as backup. Thanks