Timeline ways, we’re not given the exact date as to when this prologue opens, though Threepio has his red arm we all saw I the movie. So speculation on my part, this begins just before the events of The Force Awakens.
Anyways, Star Wars: The Weapon of a Jedi by Jason Fry opens with a Resistance X-Wing pilot named Jessika Pava who meets C-3PO in a hangar and realizes who he is and what kinds of stories he can tell. 3PO’s mention of Luke prompts her to inquire about a Luke story not as well known as his other heroic exploits. So, in his own unique way, the protocol droid begins telling her a story set shortly after events of A New Hope, when Luke, 3PO and R2D2 go on a data retrieval mission. But the simple journey goes a bit awry, when they encounter some Imperial entanglements. This leads Luke to land on Devaron for repairs, which also coincides with recent visions he’s been having. It seems the Force is directing him there. In the town of Tikaroo, Luke requests a guide to take him to what is called the Eedit ruins; the place the Force wants him to go. But the remains, he is told, are off limits, mostly by Imperial edict (whom also has perimeter alarms around the temples), but also because the place is thought to be haunted. Eventually, Luke he ends up hiring a scavenger named Sarco Plank to take him into the forest. Plank is an eyeless insectoid member of the Melitto species, who is also a amoral scavenger, bounty hunter and arms dealer. After Luke’s visions help him locate a hidden cave entrance that gets him past the Imperial perimeter, he uncovers 3 training remotes and trains for a few days at the temple before the Imperials catch up with him and the time comes to put his training to use.
There are some distant ties to The Force Awakens here, especially the notion of the Jedi Order temples we hear Han Solo talk about briefly in the film. While this is new to the movies, if memory serves me right, the Jedi temples were first mentioned in The Clone Wars animated series (unified canon, baby). And Sarco Plank appears on Jakku, but is given no real mention there.
Also, it’s an easy read (well, it is for the 9-14 range), but for fans, this gives a wider look into the new timeline created, especially since these books are now considered canon.
Not sure if it matters, but this YA title, Star Wars: Weapon of a Jedi is the second book in this Journey to Star Wars: The Force Awakens series. I was unsure if there was a certain order to them, so I started with the Luke Skywalker one first.