Q: Allah (Glorified be He) guides many people all over the world (to Islam) by virtue of
calling people to Islam at their homes and having the subjects of Da`wah leave for faithful-oriented environments
for 3 days a month, 40 days a year or 4 months in their lifetime. Actually, we systematize Da`wah efforts as such because we believe that regularity and continuity of any work, in all issues of life, can be achieved only through a good system exactly like time and attendance systems. Moreover, His Excellency the Director of Da`wah, Guidance and (Part No. 11; Page No. 30
Da`wah is a noble activity undertaken by Prophets and their followers. In this regard, Allah (Exalted be He) says:
Say (O Muhammad صلى الله عليه و سلم): "This is my way; I invite unto Allâh (i.e. to the Oneness of Allâh - Islâmic Monotheism) with sure knowledge, I and whosoever follows me (also must invite others to Allâh i.e. to the Oneness of Allâh - Islâmic Monotheism with sure knowledge). And Glorified and Exalted be Allâh (above all that they associate as partners with Him). And I am not of the Mushrikûn (polytheists, pagans, idolaters and disbelievers in the Oneness of Allâh; those who worship others along with Allâh or set up rivals or partners to Allâh)."
In fact, the system to be adopted for Da`wah should be derived from the Qur'an and the Sirah (the Prophet's biography) rather than from the methodology introduced by Islamic groups and not substantiated by any reference to the Qur'an or Sunnah. The system mentioned in the question has no grounds in the Qur'an or (acts, sayings or approvals of the Prophet); rather, it is humanly introduced, bearing in mind that everybody can have their word accepted or rejected except the impeccable Prophet (peace be upon him). In fact, any Da`wah group that does not undertake, as a primary concern, the task of setting right people's belief, propagating the Oneness of Allah, forbidding Bid`ahs and acquiring beneficial knowledge derived from the Qur'an and Sunnah from scholars is not rightly-based because in this way it does not follow the methodology of Da`wah adopted by the Prophets. Actually, the first thing a Prophet would address to his people was:
O my people! Worship Allah! You have no other Ilah (God) but Him.
(Part No. 11; Page No. 31)
When the Messenger of Allah (peace be upon him) sent
Yemen, he instructed him: 'You will be going to a Christian and Jewish Community. Invite them first to testify that La ilaha illa Allah (there is no God but Allah) and that I am (Prophet Muhammad [Peace be upon Him]) the Messenger of Allah. If they accept this, then tell them that Allah has enjoined upon them Five Obligatory Daily Prayers. If they obey, then tell them that Allah has made Zakah (obligatory charity) as Faridah (obligatory act) on them to be collected from their rich and distributed among their poor.
Therefore, the first task Mu`adh was charged with was calling them to the Oneness of Allah giving it no specific term, whether a week, month or year. No doubt, your specifying a term for Da`wah is not substantiated by any evidence. In fact, there is always a continuing need for Da`wah.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.