How much time must pass after swearing not to do something for one to do it without expiation?

If a person swears to abandon something, they are obligated to abandon it permanently, unless they intended to abandon it for a specific period, in which case they do not break their oath by doing it after that period. However, if they had no specific intention, then they break their oath by doing it at any time, and expiation becomes obligatory upon them. Therefore, unless they had an intention to specify their oath, performing the sworn-upon act necessitates expiation at any time.