***** NOT A TEACHER *****
(1) I think that I understand the problem.
(2) There is a big difference between "A year later, he took a job" and "A year later, he had [already] taken a job."
(a) If you use the past, it means that he won the lottery in, say, January, 2011, and in January, 2012, he then took a job
as a sales clerk (Americans prefer "sales associate." It sounds more elegant!).
(b) If you use the past perfect, it means that he won in January, 2011, but in January, 2012, we find him already working
as a sales associate. (Who knows? Maybe he ran out of lottery winnings in November, 2011, and started working as a sales
associate in that month.)