One thing that may help is, instead of riding for an hour or more at a time, stop every 15 or 20 minutes or so and either just stand over the bike or get off and walk around for a few minutes. You are supporting your weight on a different area of your bottom, and the pressure points squeeze all of the capillary blood out of the tissues. Getting your weight off that area helps. Standing and pedaling helps too.
Keep making little tweaks, and keep riding. It'll get better.
My experience indicates that it's not so much the Brooks getting broken-in to your butt, but your butt getting broken-in to your Brooks. I went through the break-in agony with my first B17. When I decided to put one on my second bike, there was little to no break-in. It was comfortable right away.