Alma’s prophecy

Alma’s prophecy that he had Helaman write was to be fulfilled within 500 years (we know from hindsight). Alma and Helaman both knew that it was more than 400 years in the future but I wonder if Alma was also told that his mission was concluded after he received that prophecy. Additionally, I wonder if that project stirred up an urgency in Helaman to go preach to the people even knowing that its fulfillment was not for another 400+ years.