Originally Posted by kaka

I'm not saying particularly if you should or should not do this, but you can spend a good part of 3 hours in Central (a bit more if you know what you can do in Tsing Yi or Tsuen Wan - I'd say there's next to nothing you might want to do around Olympic Station or Kowloon Station unless you want to have the Ritz Carlton breakfast)

My girlfriend landed in HKIA at 0636 today and got to HK Station at 0744. (The express train would set you back 110hkd on a DAY RETURN ticket to HK Station)
For a 1300 departure you would have needed to check in in HK Station at 1130, so you are defo safe with a train departing at 1130 (arriving 1155). For the 2 trains after you would "still be fine" but it's not something i recommend people doing (I do it once in a while by accident - i won't sweat as long as i leave the Hong Kong train station 70 minutes before flight).
The only rush hour part that I think you would run into is the people getting on the express train on intermediate stops.

At 0800 you can probably go to the Peak, have dimsum at Luk Yu/Lin Heung in Central or a local restaurant near Tsing Yi, go get local breakfast, take the Star Ferry to TST then end with the shuttle to the Kowloon Airport Express Station <strong><u>OR</u></strong> walk around Central and catch a coffee outside of the station (just 1-2 of these options!).

The big budda at Po Lin Monastary opens at 1030. you will not make it if you allocate any time to go up the budda, but nothing around the area would be open before 1030.