I pulled kindergarten into the discussion because when you list schools like Dioscesan school, yes, you DO need to start the planning process pretty early and there are very much certain kindergartens that are much more likely to result in admission. And when you produce a list that includes the very most top schools in Hong Kong, the planning must, in fact, begin at age 2. It's very much beyond most people's experience in other countries.
There's no implication that you or any other expat are not attempting to do the best preparation for your own child. I myself moved at the time of admission to both kindergarten and P1 when I lived in the US, and very much found certain school options were entirely foreclosed to me based on feeder preschools or kindergarten despite my child being bright and well prepared in other out of state kindergartens or preschools. That daughter is now 35, she survived.
I am glad you found some schools that meet your needs, at the end of the day, it's way more about finding a school that is right for the particular child rather than some school off a league table.
I will post on this forum where I like, my track record of reasonably useful posts that do not denigrate others is a good one.