I just did a "tummy check" on Jimmy, searching for fleas, and I see none. His skin looks less red and angry, but the insides of his back legs and tummy still look hive-y. Spots that he chewed raw, now look "calm", with healthy-looking scabs.
I guess the million-dollar question going forward, is if every flea bite will cause more hives? Obviously, time will tell. My understanding of Bravecto is that it kills feeding fleas, so they will still jump on Jimmy and bite. While I'm not keen on having a systemic insecticide residing in my dogs, it's more important to have them comfortable and not chewing themselves to shreds. And since Ben also had fleas - he's sort of my "control" dog. He shows no effects from the Bravecto except that he no longer stops what he's doing to scratch at a flea. So far, I'm pretty impressed with the product.