Some headcanons regarding Killian's age.
Assuming he's physically around the same age as Emma and the Charmings (Colin is actually younger than JMo).
He was probably in the navy for a few years before Liam's death.
He was probably a pirate at least a year or so before he met Milah.
Based on Baelfire's aging Killian and Milah were together around 4 years. Milah was killed while Baelfire was in London as Hook was already in Neverland when he arrived.
Hook was present in the Enchanted Forest at least a year before the Dark Curse. Unclear when he permanently left Neverland.
Emma breaks the curse sometime after Valentine's Day 2012 (Skin Deep) and ends up in the Enchanted Forest shortly after.
They find Neal in New York and Hook stabs Rumple sometime after Aug 15, 2012 (Henry is 11).
It's fall or winter when they get back from Neverland.
It's winter or early spring a year later, 2013-2014 when they fight Zelena.
The S4 period of peace occurs during winter 2014-2015 (Rumple was in the hospital around Christmas)
The Camelot weeks occur before Aug 15, 2015 (Henry is 13)
It's winter again when Gideon sends Hook away in S6.
S7 Storybrooke is set around 4 years after S6 (Robin II is 5, Neal II is a child).
Henry spends a few years in the New Enchanted Forest before meeting Ella and being reunited with his moms and Hook. Unclear whether time has passed in Storybrooke.
Wish!Hook is 28 years older since the Wish Realm had no dark curse. Alice is born not too long after Regina's defeat.
His heart was cursed when Alice was around 12.
Wish!Hook spends at least 8 years (Lucy's birth and childhood) with Henry and Regina in the New Enchanted Forest between being de-aged and being sent back in time by the new curse.
