I would suggest you to mail enough quantity of concentrate formula to HK before you go for your trip. Unless you may need to give your baby another formula. In HK, powdered formula is most common and also the current brand you are using may not be available. Even with the same brand, the taste, composition should be a bit different.
花旗太太生活在花旗國,留意時差,你問我未必即時答到。