Don't eat anything until the numbness wears off. Your tooth may continue to feel sdifferent from your other teeth for some time after your root canal treatment has been completed. If you have severe pain or pressure that lasts more than a few days, contact the dentist.
Usually very quickly a week or so at most. People tend to assume that a recently-treated tooth is going to take weeks or months to heal. Most people don't feel pain or notice any difference in how they feel 48 to 72 hours later, though sometimes it may take longer.
The root canal procedure itself is normally painless. A local aesthetic numbs the tooth and the surrounding area.