Says i09, “Although it’s possible in the world of Star Wars, which is full of clones, ghosts, laser swords, and weapons the size of small moons and planets that Palpatine bore a child through means beyond traditional procreation—a manipulation of the Force akin to Anakin Skywalker’s immaculate conception, the aforementioned cloning or some other genetic manipulation, perhaps even surrogacy. But there’s a far simpler alternative: Palpatine met a woman, perhaps even fell in love, and then, well, told her the tragedy of Darth Plagueis the Wise, if you will.”
Thanks to the Star Wars Visual Dictionary books, we know that Rey was born in 15 ABY—that’s “After the Battle of Yavin” in Star Wars chronology, so 15 years after the time of A New Hope. the most recent visual dictionary for Rise of Skywalker brought in a new time measurement that reframed galactic events around the destruction of Starkiller Base (BSI and ASI, “Before and After the Starkiller Incident”) in The Force Awakens.
That new book tells us that Rey is approximately six years old when she is left on Jakku by her parents in 21 ABY—her father, the son of Palpatine (played by Billy Howle), and her mother (Killing Eve’s Jodie Comer)—as they attempt to flee the wrath of Palpatine in the form of Sith-obsessed assassin, Ochi of Bestoon. Ochi and his ship, the Bestoon Legacy, catch up with Rey’s parents shortly after this: the Rise dictionary tells us that her parents perished 13 years before the Starkiller incident. Given that The Force Awakens takes place in 34 ABY, would make their deaths also take place the same calendar year Rey was abandoned on Jakku.
That would mean he’s been active and searching for 23 years.