The best time is at 3:30am. You need to draw a line of chalk around your mouse, then turn in 3 circles COUNTER-CLOCKWISE. Then, you break a small section of the chalkline, then turn 5 times CLOCKWISE.
Do this before every run, and do not MF past 5:30am. You'll find runes EVERY run.
MF is not all luck, it's probablity(sp)... you might make a game .01 seconds faster during the night (non peak hours) then during the day (people leave bots on during work/school, most don't leave them on at night)