Help with using monostable one-shot multivibrator?
A typical one-shot mono stable triggers if only the input is as such i.e. HIGH-LOW-HIGH

Hence the monostable triggers on falling edge of the input. If you invert your input signal you will get desired output. 

Here's a example input-output waveform from NE555 Datasheet.
T = 1.1 RC 
So 560 ohm and 1uF cap will give you 616 uS on time.