it usually happens when the plane is at the gate and they want people to board more or less on time, hence the slight delay in the departure time, but currently they have a very late slot to take off so they estimate that late landing. So probably you will board the plane then either sit for a long time, don't worry you will leave the gate area but then they move it next to the runway in a holding point. (Done that a few times) or if you lucky they will find a slot earlier and the landing time will improve.