A little further on in the chapter (A Knife in the Dark), immediately following your quote regarding the hobbits blowing their horns, we have this:
Quote:
|
Meanwhile they had another errand: they knew now that the house was empty and the Ring had gone.
|
Therefore, up until they had broken into the house, they were not sure if the Ring was in the house or not. If they weren't sure of this, then it is likely that they weren't sure of many other things, such as Fatty escaping.
I also still think that there was a simultaneity to the attacks in Crickhollow and Bree, and that was part of their plan.