Great thread, as for the past month or so, I've been giving our 9 month old snake 3 pinkies at feeding time each week; dropping one in at a time and then going back to give him another. I just increased our second snake to 3 pinkies as well. A month or so back, I bought one of the next sizes up but it just looked to think to give him.
Our snakes are getting longer, but not thick enough from what I would think necessary for the next step up.
Any other general rules on this? Next time I feed him, this Thursday, I'll take a photo of his lump; although, with 3 pinkies in him, it's a longer stretched out lump. You can see the lump, medium in size I would say; by day 3 after feeding, any sign of a lump are gone.