Sleeping pills can take between 15 to 30 minutes to kick in and make you feel sleepy.
If the sleeping pills are not making you sleepy within 30 minutes you might need to take 2 sleeping pills to up your dose.
You should be drifting off to sleep and feeling very drowsy within 30 minutes at most and if not you may need to take another sleeping pill.
I'm usually out within 30 minutes of taking my sleeping pill so I take the sleeping pill 30 minutes before going to bed.