Answer:
Around 600+ AD
The first mesaage that Muhammad received was that allahtold him that you are my prophet and you will spread Islam
the allah is one and muhammad is the messanger of allah
because prophet Mohammad [saw] is the messanger of Allah
There is no God other than Allah and Muhammad is the messenger of Allah
there is no God but Allah and Muhammad (PBUH) is messenger of Allah and people can go Heaven by submitting to Allah
messenger of Allah , sent to deliver the message of Islam
To believe in, obey & worship the only ONE God "Allah",with nothing associated to Him at all, no parents, no son, no partner, no similar.
In Islam, Muhammad is considered the last prophet and messenger of Allah. He received revelations from Allah which form the basis of the Quran, the holy book of Islam. Muslims believe that Muhammad conveyed Allah's message to humanity and served as a role model for how to live a righteous life according to the teachings of Islam.
Prophet Muhammed had received a message from ALLAH, and from that day on it spread.
Muhammad did not "found" Allah; rather, he is considered the final prophet in Islam who conveyed Allah's message to humanity. Muslims believe that Allah is the same God worshipped in Judaism and Christianity, and that Muhammad received revelations from Allah through the Angel Gabriel over a period of 23 years. These revelations were later compiled into the Quran, the holy book of Islam, which outlines the beliefs and practices of the faith. Muhammad's role was to guide people to worship Allah and live according to His will.
Muhammad PBUH is the last ,the greatest & the most important prophet. Also, He is the best human ever & forever. He was chosen by the Almighty Allah to convey the message of Islam, the last & universal message from Allah to the mankind. For more information, refer to the related question below.
Prophet Muhammad (Peace Be Upon Him) is messenger of Allah. Allah sent him down to Earth to give the message to mankinds about Islam in order to worship the one and only God which is Allah, the Almighty and that we all can have the opportunity to do good deeds as we are striving Allah's rewards in the Hereafter which is Paradise that is known as Heaven.