I have a different opinion .....I would say that since you have only been open for 4 months that you should change your contract so that all new families coming in will be paying stat holidays and leave the ones on current enrolment as they are for the first year. As a parent I would not be impressed if you started changing things so quickly. These parents may have signed on with you for this reason and you have to decide if its worth losing them over. However if you waited a full year then these parents would be more likely to agree as their children are settled and happy, and they would be less likely to want to change providers.