Most people who have tonsillitis recover fully from the tonsillitis within 4 to 10 days.
If your tonsillitis lasts longer than 10 days you may have a more severe bacterial infection and should let your doctor know about it.
You might need a stronger antibiotic to recover from the more severe bacterial tonsillitis than your normal antibiotic would be able to cure.
The last time I had tonsillitis it was gone within 7 days but sometimes tonsillitis can last for some people up to 10 days and if it lasts longer than 10 days then something else could be wrong.
You may also have Chronic tonsillitis and should see your doctor more about it.
However most cases of tonsillitis are not that severe and go away sometimes on their own within the 10 days but sometimes it may go away within 4 days.