The nicotine patch should kick in and begin working within 10 to 24 hours.
It can take up to a few weeks of wearing nicotine patches to fully stop the nicotine cravings so just keep at it and continue to wear the nicotine patches until the cravings for nicotine go away.
Some people may notice the cravings disappear within a week while other people may not completely stop the nicotine cravings until a few weeks.