(Source - My many years on fighter jet flightlines. F-111E, F-106, F-15, F-16)
The designated jets are fully preflighted. Munitions fully loaded. INS aligned, IFF code laid in, most but not all of the safety devices removed. The jet is ready to go except for the pilot and engine start.
Assigned alert pilots and ground crew are hanging around. ...
Typically you would do a preflight like this, but it's obviously different from place to place, depending on local requirements.
Before placing the aircraft on quick response status, you would do the normal preflight procedures like inspecting the aircraft exterior, checking cockpit, following your pre-engine start check, and starting the engine.
After this, ...