AI bombing drop delay

[EG14_Marcast]

Is it possible to set the bombing drop delay for AI planes? In a bombing mission with Ju88s I set the waypoint over the target (an airfield) as "ground attack - area", level bombing. All AI planes drop at maximum delay, and as the target is not so big many bombs fall out of it. I tried also "ground attack - target" without setting the target, but in this case the planes don't drop at all.