To start things off, here is a BATF report of their activities on February 19, 1993, nine days before the first raid and gun battle.
Background: BATF claimed that the massive raid (80+ agents, three borrowed military helicopters, a large caravan of vehicles) was necessary because David Koresh was a paranoid recluse who never left the Davidians' building and thus could not be arrested peacefully.
To monitor the Davidians, BATF put several agents in what came to be called the "undercover house," across the street from the Davidian residence (albeit "across the street" here means a couple of hundred yards away). This report details what those agents did on February 19.
They went shooting.
With David Koresh.
They had all the guns. Koresh had one unarmed Davidian with him. Then Koresh went home, and the agents went back to planning the raid.