Turns out my theory of how the timeline could be incorrect as in the episode "Model Students" when Zack is manipulating Kelly to stay, one of his tricks is to make Screech pretend to cry and make up a story that he is crying because Kelly is missing his birthday next week. My theory said most of season 2 exculding some episodes are set in the same year but in Season 1 we already had an episode dealing with Screech's Birthday meaning that Season 1 must be their freshman year (despite some inconsistencies) as by "Model Students" it would've almost a year since Screech's Birthday since Zack mentioned it again. This probably a continuity error but still couldn't help not point it out. Unless to go back to Alternate Reality theory of this being another reality we looked at.