Prophet Muhammad (sws) was a Rasul in addition to being a Nabi. It is evident from the Quran that all prophets of God were sent to call people to God and to warn (indhar) and to give glad tidings to them. Those who were given the status of rusul (messengers), their indhar (warning) culminated in shahadah. In the terminology of the Quran, shahadah means that the truth is communicated to people in such a manner that no one is left with an excuse to deny it.
Therefore, the whole life of Porphet Muhammad (Sws) after his prophethood had been in a constant state of Preaching (Tableegh). It is neither practically possible nor logically fair to divide it into hours of a day or days of a week. The law of preaching for a Rasul is different as compared to other Muslims who want to do preaching. Prophet’s (sws) preaching was divided into different phases depending upon the stage of Indhar namely:
i) Indhar (Warning)
ii) Indhar-i Am (Open Warning)
iii) Itmam-i Hujjah
iv) Hijrah and Baraah (Migration and Acquittal)
v) Reward and Punishment
Details on Islamic Sharia of Preaching can be found here:
Discussion 27858