I have noticed this and don't tell me i'm the only one.
Better users seem to get on at late hours of night.
So I just whipped up a handy-dandy little equation to help you find when certain users may or may not get on.
BL_ID/60 x ({4+[12/6]/[34-33] - [6/3 x 3]}/stuff going down) = forget my eyes ≧ Profit
Or a simpler one: BL_ID/120 = amount of hours before/after midnight a wild BLFer will appear