There's a pattern here. Quite a few people seem to be getting the Miner, Nuturer and Slayer in the last few days. Assuming that most people collect from mines roughly the same number of times a day, that makes sense if the Miner badge reflects a certain number of collections. Likewise with slaying monsters; it makes sense we would all hit it around the same time. So I am guessing we will all start to hit the next one at around the same time too, dependant on what has been your focus is the game.