During December 12 to 20, how many hours earlier than the flight depart should we arrived the airport for check in and security checking?

Depends on DOMESTIC or internation and each airline is SO different. Take Alaska vs Southwest! Or United vs Hawaiian!So call your airline.

arrive at least 2 hours in advance prior to your flight, to leave enough time for baggage check in, and security.

2 hours quite rush. Better at least 3 hours before departure

2 hours for domestic and 3 hours for international flight.