How important is Cantonese when kids apply to local schools (ESF particularly)?

Hi! We are an English couple with a new baby, looking to stay in Hong Kong for the long term, in part due to the excellent schools here. We are very keen for our child to grow up fluent in Mandarin as well as English and happy for them to learn Cantonese so that they are part of the whole society far more than their parents are now given we both only speak English fluently. We have thought about this a bit and we are less excited by the idea of sending our kids to a private international school because we feel that:

a) the children (and staff potentially?) will be more transient there.
b) fees are high.
c) we hear that Mandarin is often not as good as at the local schools.

That said, we recognise that academically a lot of the best performing schools are the private ones (!). Our ideal would be to get our kid in to a high quality ESF school, however I know that it is very hard to get in to the ESFs. We are wondering what will go in to the decision making for kids to get in to the ESF schools and whether there is anything we need to do to improve our chances. Also, in particular, how important will a child's fluency in Cantonese be?

There are lots of nursery schools that are bilingual in English and Mandarin but not a lot of Cantonese ones. If we put them in to one of these will we risk being rejected from a local ESF school because our child may not speak Cantonese as well as some of the other kids? It feels a long way off to be worrying about these things now but if our child really needs to have good quality Cantonese I'd rather know this now than regret it later!

Is there anything else major to consider about applying to the ESF schools that we should be aware of?

Thanks!

Hi! Londonboy78, we have exactly same concerns for our children. We also recently moved to HKG & we plan to give best of available to our kids at affordable resources. For the time being we got our children admitted to nearby kindergarten at Upper KG. We are even more worried as our children are already approaching primary one admission level. Would be grateful if you share more knowledge on this journey ahead. We would do the same. Thanks.