Welcome to my current hyperfixation, creating as accurate a timeline as possible for the life (until 1st death) of one Phillip J Coulson, under the cut for your convenience
Born in Manitowoc WI to history teacher and football coach Robert, and homemaker Julie Coulson.
Played Little League (batted .400), fixed up a cherry red 62 Chevy with his dad
Death of his father, circumstances unknown, but was considered a Defining Moment in his life. He's "forgotten more about [his dad] than he remembers." He and his mother then moved away from Manitowoc.
First contact with SHIELD, right out of high school. Canon differs on whether he was recruited straight out of senior year or simply tapped and recruited after some college (reported history degree which got him on SHIELD's radar, but Coulson personally said "younger than [Skye, early 20s] when I was recruited, straight out of high school." My personal thought is that he was approached during/just after high school, but was encouraged to get a degree to help him get into SHIELD Academy
Formal recruitment into SHIELD Academy of Communications, to study data analysis and become "The analysis expert" -Agent Tripp.
Coulson + Melinda May's first mission, in Sausalito, CA, with no proper exit plan that ended with May stuck in the bay for 5 hours.
(this year, presuming he entered SHIELD Academy after a 4 year college degree, is exact and lines up better with him being a Junior Agent in Captain Marvel, 1995. According to Jemma Simmons' stated biography, the Academy is a 4 year program. When undercover in HYDRA she stated she started at SHIELD at 17. She was born in 1987 and graduated the Academy "in 2004, 3 years early" meaning she only spent 1 year there max. She could not have entered the academy any younger for multiple reasons (had at least 1 PhD, and to gain a visa to study/work younger than 17 would have been nigh impossible))
Ran multiple missions with Katherine Shane and presumably had a casual relationship
Junior Agent Coulson, along with Nick Fury, is tasked with investigating an unusual circumstance at a Blockbuster in LA. Plot of Captain Marvel happens here, along with the first mention of the (currently unnamed) Avengers Initiative. At this time Coulson does not know the true story of how Fury lost his eye
First meeting with Audrey Nathan (the cellist and proclaimed Coulson's true love). Proceeded to start a relationship, including trips to Hawaii (to get a tie as a gift and eat some poi) and dinners at The Richmond
Marcus Daniels' wiki says he was in a lab accident at college sometime between 1992-96. Watsonian logic, Coulson was likely picked for the case because of his previous experience with light-based powered persons
Recruitment of Clint Barton
Wiki says he was hand-picked by Fury in the early 2000s. He met Laura working with her at SHIELD and his oldest daughter was born around 2004.
Coulson stationed in Cusco, Peru alongside Camilla Reyes, a member of Policia Militar del Perú, with whom he formed some form of romantic/casual relationship.
Best guess, Coulson considered all his relationships casual/incidental, saying goodbye to Audrey each time and hoping to be able to come back but making no promises of fidelity. Either that or he's a prolific cheater because Marvel can't get their stories straight. I prefer option A.
Promoted to training teams of agents
Between being an attache to a foreign governmental body and gaining Akela (next bullet), a notoriously difficult recruit, he had to have cut his teeth training other teams/agents. Akela's training absolutely falls under this timeline as well, given how well she knew him
sent his recruit Akela with a small team to raid a gulag owned by criminal Vanchat, where Akela was either captured or killed somewhere in the Shanxi Province, according to record.
2008, likely early spring
Coulson and May were sent as the Welcome Wagon to talk to a possible gifted in Bahrain, resulting in the birth of The Cavalry and May's cold personality change
Word of The Hulk reaches SHIELD. Coulson questions whether Fury wants to fold him in, to which he's told the Hulk is "Thunderbolt Ross's problem"
Sent as the Welcome Wagon to recruit Tony Stark to SHIELD after his return from captivity under the guise of a debrief
Sends Agent Barton on a mission in Russia in which Barton runs across the Black Widow. Barton is then sent back to kill her, resulting in a standoff in Budapest, days off grid, the death of a young girl, and the recruitment of Natasha Romanoff
Takes up overseeing the TAHITI project (in 2014 one of the agents who had taken part and was wiped was officially declared dead 5 years previous). Also shuts down the project due to the insurmountable issues presenting in the subjects.
Sent to babysit Tony Stark on his house arrest, threatening to "tase him and watch Supernanny while he drools into the carpet"
Sent to investigate an 084 alongside a science team and Agent Barton, resulting in the plot of Thor
Captain America found in the ice. Defrosted and set up in a 1940s dummy hospital setup, presumably planned by Coulson, the resident expert on Captain America, history, and gifted recruits. Plus he "watched Steve while he was sleeping"
Hawkeye is assigned to infiltrate the helicarrier under Fury's orders and learns of the Avengers Initiative, as well as Coulson's involvement.
Coulson dies. Had a date planned with Audrey in Portland, missed it due to gaining a new piece of Asgardian hardware in his chest
Coulson undergoes multiple invasive surgeries in an attempt to revive him using Kree blood as part of the TAHITI project.
Starts up a new team composed of Melinda May, Grant Ward, Jemma Simmons, and Leopold Fitz to take on interesting problems, functioning as a quick-response unit (and to allow May to keep a very close eye on Coulson)