The operator will get the slot almost as soon as the plan is filed (often in the very very early hours of the morning).
Everything after that is dynamic with revised slots, cancellations, etc, being dealt with as soon as they are calculated.
The operator has the information, and they are also the ones who have the relationship with the crews and pax
Quite rightly they aim for the original departure time since the slot situation can change very quickly and the 1 hour delay can suddenly disappear. That's not much good to the company though if you are still in your bed when you should be in the P1 seat
