- School Western Connecticut State University, University of Bridgeport
- High School Plainville High School
DeJohn started his coaching career as an assistant coach at Western Connecticut in 2007 before moving to high school coaching for several years. He was an assistant coach at Plainville High School, his alma mater, in 2008-2010 and helped lead the Blue Devils to a state championship in 2008. DeJohn then moved to Southington High School as an assistant from 2011-2015. He moved back to the college coaching ranks with the University of Hartford Hawks in 2016-2017 and the University of Memphis Tigers from 2018-2019.
DeJohn got a taste of professional coaching during the summer of 2019 with the Milwaukee Milkmen of the independent American Association. He joined the Baltimore Orioles organization in November, 2019 as a development coach for the GCL Orioles. Unfortunately, he didn't get to coach since the minor league season was cancelled due to COVID-19. DeJohn was fundamentals coach for the Aberdeen IronBirds in 2021 and Bowie Baysox in 2022.
Tim is the son of Mark DeJohn, a long-time coach and manager in the professional ranks.