According to the chief's interview that I saw, the Deputy that was on scene at the start had a gun battle with the Shooter and he chased the shooter inside the club, where he barricaded himself into a bathroom with 30 hostages.
At that point, SWAT had to decide how to save those hostages. If they tried to break into the bathroom everyone would die right then. But the shooter was calling LE and 'negotiating. He made 3 calls. So I understand why the cops were waiting him out. At one point they finally knocked down a back wall and let some survivors out.
I liked what Los Angeles Chief of Police said, about people second guessing the Orlando chief's decision. Beck said " I must have a really easy job because everyone else knows exactly how to do it right except me...'
With 20/20 hindsight we can say they could have or should have gone in earlier. But they were in an armed standoff hostage situation and they thought there were explosives as well. So...?