Aries: 24 hours top
Taurus: until they die. Maybe not even then.
Gemini: give it 30 seconds
Cancer: years
Leo: until the end of time
Virgo: couple of months
Libra: 2 seconds unless you really fucked up
Scorpio: all of eternity
Sagittarius: two days
Capricorn: don't even bother apologizing
Aquarius: a year
Pisces: 2 months maybe