All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
In general, Islam recommends the mention of Allaah and the exaltation of the mention of the Prophet in every Muslim meeting. The Prophet said: "There is no people who sit in a meeting and who do not mention Allaah nor exalt the mention of the Prophet except that it will be a sorrow on them and they will regret it, if Allaah then wishes to punish them, He will, and if He wishes to forgive them, He will." [At-Tirmithi] Therefore, this act [mentioning Allaah and exalting the mention of the Prophet ] is something which is legislated in principle, but this should not be according a particular definite pattern or definite number of times, so that the matter will not cause confusion to the people to an extent that they will think that this manner of doing the mention or stating it a particular number of times is the Sunnah.
Allaah Knows best.