Timeline Facts Not Made Clear in the Movie
Based on reading the Wikipedia bio of Kurt Warner there were 4 football seasons between his graduation from college and his being signed by the Rams. One season he spent continuing his own training at home and working at the grocery store. Then he had 3 seasons as an arena football quarterback.
He was then signed by the Rams and sat on the bench for one season before becoming the starter in '99 and taking the team to the Superbowl.
My impression from the movie was that he became the starter at the beginning of his first season with the Rams, but it was actually his second season. I also felt that the movie left it very vague how many years went by before he found his way into the pros.