my kids also changed schools during K2, first you need to know your kid's type, does he/she easy to adapt new environment, also you needs to explain why he / she needs to change KG, if he/she is willing, then he / she will more easy to accept the change. If not, then you might thing about that because if your kid needs 3 months to adapt, it may affect the progress of learning. Also, it's unknown whether the kid is really like the new school / teachers/ classmates.
My kid also changed to PHT/ENG KG, his ENG teacher said he speaks a lot, but PHT teacher said he did not speak a lot. The reason is he can't use PHT to express even he understand PHT's say. In K3, the situation is better, but he talks moer in Eng class.
He took at least half year to adapt the new teaching language and new school. I think that the choice is depanding how do you like to have PHT to learn Chinese. I think the expression must be more comfortable for my son if he is using Cantonese. But I want to use PHT as ealier as possible and I can't speak PHT very well, so that I can't teach him.