The scholars and jurists in Islam are absolutely unanimous in their opinion that there is absolutely no minimum period one may intend to observe the worship of ‘Itikaf’. As long as one makes the intention to observe the ‘Itikaf’ and dedicates oneself to the worship and rememberance of the Lord, even if it be for a day or a night, or a part of the day or the night, one would be considered to be in the state of ‘Itikaf’. If one wishes to observe ‘Itikaf’ for a full 24-hour period of the day, or only a part of it, they are well within the boundaries to do so. ﴾الله أعلم بالصواب﴿
And Eid Mubarak in advance!