Sozee, I believe you should be able to check in for your 14:45 flight during the first opening period, since they allow online check in up to 48 hours prior to departure, as long as you're not checking in bags.
For bag drop, per
https://www.cathaypacific.com/cx/en_...l-airport.html
Note: Please note that passengers are able to print their own baggage tags at the Self Check-in Kiosk, available between three hours and 50 minutes before the scheduled time of departure of their flight.