How long generally does it take a sleeping pill to take affect?

30-60 minutes. Most 'sleeping pills" should start working within half an hour, gradually you dose off and fall to sleep. Each one of us responds differently. It depends if your stomach is full or empty, depends on your anxiety state and stress tolerance. So many factors. But bottom line do not get dependent on sleeping pills.
Depends. It generally depends on the pill, the absorption of the pill and the tolerance to the pill if you have been taking it for a while. Some act right away, while for others it could be up to an hour depending on the pill. Sorry i could not be more specific but the range of possibilities is huge.
Insomnia . The sleeping pills usually take sometime between 15-45 minutes to be affective.