2. Ben Finney, Finnegan and Ruth: Kirk is Academy plebe at 18. Add 15 years and Kirk is 33 during Shore Leave. Ruth is an older woman who is Kirk's first love ("Maggie May".) Also, befriends older, married Ben Finney (either instructor or noncommissioned officer with a new commission to Starfleet). Finney's first child is born and named after James. Jamie would be at the oldest 15 during CM even if Mrs. Finney was very pregnant when they met. Jamie's probably 14.
3. Events of the Cage: 13 years prior to The Menagerie, making Kirk about 20. No indication of any recent war, since Pike doesn't sound battle-hardened; moping about losing 3 crew lives. Hell, Kirk loses 3 crew almost every other episode.
4. Kirk is ensign. Junior/Senior year at Academy and serves on U.S.S. Republic as an acting ensign; making him 20-21. Was this a training vessel, or a potential wartime conflict, where they pull up upperclassmen to serve on ships to fill the ranks. Ben Finney serves with Kirk. Something odd is happening. Possibly the "Axanar Peace Mission" reference?
5. Kirk is lieutenant. Graduates from Academy, age 22 with lieutenant commission (rare, something odd has happened) and serves on U.S.S. Farragut under Captain Garrovick. Garrovick gets killed and Kirk blames self.
6. McCoy's Comment: Kirk is lieutenant 11 years prior to TCM; making him still 22, and based on McCoy's comment about Bailey, perhaps a little damaged.