Several factors would need to be taken into consideration. How serious was the sin/offense? Is it well known with-in the congregation and general community? What was the attitude of the person when the person was approached either by another brother or the elders themselves? Circumstances that led up to the sin/act? There seems to be no time quota as such. In one congregation here in Tasmania one brother was re-instated after 3 months and in my own congregation, a brother had to wait for 7yrs 6 months, due to the wide spread results of his actions. Acts of genuine repentance is the key and Holy Spirit guides the panel of elders dealing with the issue. Jehovah then is the final judge.