Landing in Hong Kong International Airport at 5am.

Dear, to be honest, you are not advised to get to Guangzhou if you want to go for the sightseeing because it is too tight and complicated.

Here are the details: You can take the direct bus from HKIA to Guangzhou after about 06:00. And the bus ride may need about 3.5 hours. So you may get to Guangzhou at about 10:00. You have to reserve about 2 hours for boarding the flight, so you need to get to the airport from Guangzhou before at about 04:00pm. So you have to leave Guangzhou for HKIA at 01:00pm and you only stay for about 2 -3 hours in Guangzhou.