Bear in mind that Easyjet expect to turn round an A320, with more passengers that BA, in 20-25 minutes at the bulk of their outstations.
Easyjet also make use of both front and back doors which makes a huge difference to the turn around time, especially the onload, where-as BA, at most stations opt to use the Airbridge. Some stations use an Airbridge and back steps like EDI and GLA for both boarding and disembarkation. However, this is not possible at every station due to which side of the aircraft is used for fueling.
yes we do have some minimum turnaround times, the 319 is 35 mins, 320 40mins whilst the absolute minimum is 45 mins for a 321.
The clock starts as soon as the brakes are applied. This is the 'On-chocks' time. So, if we take a typical fully loaded (132 seats) A319. The turn would be as follows:
*A/C arrived on stand on the hour - lets say 12:00
*12:01 Bridge attached (Lets assume Airbridge only used)
*12:02 First passenger disembarked
*12:12 Last passenger disembarked
*12:12 Cleaners board the aircraft
*12:17 Boarding down the airbridge commences
*12:21 Cleaners leave aircraft (Cleaners given 9 mins max)
*12:22 Boarding onto aircraft starts
*12:32 Boarding complete
*12:32 Doors closed (BA require doors to be closed 3 mins before departure)
*12:35 Aircraft pushes back
In the above scenario, there is absolutely no slack to be had, and some turn arounds can also include Cabin config changes, Crew changes and catering changes.