They didn't go home at 3 am. The first wave of SWAT team (they do NOT do forensic investigation or the actual execution of search warrants, as a rule) left, BK left, etc.
THEN, the warrant process began. Probably at dawn as you suggest (although looking around a place at different times of day can be interesting).
There's no way they did the whole search warrant in the middle of the night. I bet it took 2 hours just to remove BK from the scene, even though he was physically in their control within minutes of breaking down the door. LOTS of procedures, reports, superiors to call, etc.
And, I would submit, that the warrant may still be ongoing - do you have evidence that it's not? IMO, it can take a few days.