Following the turn sequence gives you the answer. Davout could issue new directives to his divisions on turn 1 (in the Command phase, the Issue Orders step comes after the Activate Orders step), but the new directives couldn't be activated until turn 2.
I will add, there is no reason you can’t issue an order (either an objective to a Force or a directive to a Formation) early on and choose not to roll for activation until later. Therefore, you could issue an objective on turn #1, activate it on turn #2, then issue a new objective on turn #3 but not roll to activate it until some turn in the future. Thus, in a functional way, decreasing the delay to 0.
Consider that this was essentially what happened with Soult at Austerlitz. He had an objective of The Pratzen since before the game (battle) started, but it wasn’t rolled for until the opportune turn.