How long is it supposed to it take for an appendix to rupture?

2-3 days: Once appendicitis begins, the appendix will typically rupture within 2-3 days, if left untreated.

Around 72 hours: Appendicitis can progress to rupture after 48- 72 hours, however, every case is unique.

Depends: In the very young the appendix can rupture in less than 24 hours of symptoms. If the cause of the appendicitis is a fecalith(a hard nugget of stool which obstructs appendix) the progression of disease is faster.

Hard to say: Since the onset of symptoms is often difficult to pinpoint, actual timing is always speculative.Sadly, in spite of new diagnostic aids like ultrasound or ct scan, the percentage of leaking/ruptured appendices has not declined as rapidly as we would like.