Check the carotid pulse for 5-10 seconds. If you feel no pulse within 10 seconds, start CPR cycles of 30 chest compressions then 2 breaths. Compress the center of the chest hard and fast (atleast 2 acheiving at least 100 compressions per minute) Allow for full chest recoil after each compression.
Carriers are required to provide adequate food and potable drinking water for passengers within two hours of the aircraft being delayed on the tarmac and to maintain operable lavatories and, if necessary, provide medical attention.
This was at Terminal 2 (I think) and the flight arrived late at night. So it took me 25 minutes (to the car park not the train station), please remember this is my experience and it could take longer for you. You have to take into account: flight delays, baggage delays, queues, crowds, getting lost etc.