Since there are no levels in the game I guess I have to ask when did you let your Jedi characters get their kyber crystals (experience point wise)?

One assumption I'm making is that you give 5-10 xp/session. The only guidance I see in the FaD book is that characters should have them before knight level play (150xp).

I thibk the books suggest 5 points per hour of play although if you play multiple times per week Id say 5-10 per session might be reasonable. My group plays fortnightly and often misss a session to end up once every 3-4 weeks and get 20-25 xp for a 4-5 hr session.

When you feel that it's right for the character.

Per wisdom I haven't heard on the Order 66 podcast, if you haven't given them the opportunity to get a kyber crystal by 80 earned XP, you should do it then.

Frankly, it varies.

The FaD Beta introductory adventure gave PCs kyber crystals at the conclusion, albeit ones that were not as awesome as your standard Ilum crystal as it only had about half as many modification options.

The GM Kit adventure, which is intended to either be run as an introductory adventure or as a possible follow-up to the Lost Knowledge adventure from the FaD core book, awards the PCs with Ilum crystals (they're called rubat crystals, but mechanically they're Ilum crystals).

The TFA campaign I'm playing in, my Shien Expert didn't get his kyber crystal (an Etaan crystal) until we'd hit the 165 XP mark, just past the Knight Level threshold, but that was more to the course of the story (GM had planned it out fairly early on as to when my PC would get the crystal).

So honestly, about the only real guidelines to "when should my PCs acquire kyber crystals?" are "when the GM feels comfortable awarding them" and "preferably sometime before they hit Knight Level."

This is a very narrative-focused game, but there are some mechanics involved with lightsabers that bear examination. For instance:

• However your PCs fight now, any PC who gets a lightsaber will want all of his combats to be at Engaged range (at least until one of them learns Saber Throw)
• There's a very good chance that a PC that gets a crystal will take over the role of preeminent damage dealer. If your PCs are doing fine in combat right now, without lightsabers, they'll start mopping the floor with your minion groups as soon as they transition to lightsabers
• Critical hits will become much more common, so you'll really need to know how they work
• Similarly, Breach and Sunder will get tossed around frequently. That heavily-armored, blaster-proof Rival/Nemesis that's been giving the PCs grief? He's toast.
• If you're playing in the default timeline, lightsabers are illegal. PCs that use them in populated areas (and, it should be said, leave living witnesses) are drawing the wrong sort of attention to the party

If it sounds like I'm trying to dissuade you from letting them earn a crystal, that's not the case. Lightsabers are fantastic weapons, quintessentially Star Wars. I just want you to be aware of what you (as the GM) are getting yourself into so that there's no knee-jerk reactions or pushback.

One thing to bear in mind is that while a PC with a lightsaber is likely going to be the party's big damage-dealer (thanks mostly to the Breach 1 quality) when fighting character-scale enemies, that's not to say that other PCs can't compete or even surpass the 'saber monkeys. I'm in an on-hiatus AoR game where in terms of raw damage output, my Shii-Cho Knight plays second fiddle to the BH/Gadgeteer with his heavy blaster rifle (the one from Dangerous Covenants that drops autofire in favor of Pierce 2) to which he's added further attachments (and successfully modded) in order to further crank up the damage and Pierce rating; it could probably rival Chewie's TFA Bowcaster in the ability to deliver flying bolts of "STFU&GTFO!" to the bad guys.

But SFCSnuffy is right in that introducing lightsabers into combat is going to change the dynamic of those fights considerably. They are very powerful weapons, even if just using the basic Ilum crystal; some of the variant kyber crystals can be even more of a game-changer, even if just due to the special qualities they feature, like the Lorrdian's boost to melee and ranged defense or the Etaan's (Endless Vigil) free rank in Parry and Reflect as well as the boost to Improved Reflect's damage.

Since there's no real guidelines on how to create a "balanced" combat encounter, as a GM be prepared for the first couple fights your PCs get into with their newly-constructed lightsabers to be a lot more one-sided in their favor. But this isn't a bad thing, as it lets the players enjoy their new toys. Just be sure as the GM to gradually ratchet up the difficulty of those fights, either by increasing the number of minions in a group by one or two, or adding another minion group to the combat. Also considering adding Rivals that make your minion groups more effective, but again don't do it all at once, but gradually.

Another thing to keep in mind, especially if you're playing in the Dark Times or Rebellion Era is that being seen brandishing a lightsaber automatically marks the person as a Jedi in the eyes of the public, and generally speaking the Jedi do not enjoy a good public image during the Empire's reign. Many well-meaning bystanders that would have been willing to help you out will rush off to report you to the Imperial authorities if they think you're a Jedi, and this becomes more and more true the closer you get to the Core Worlds (where Imperial propaganda is at its strongest). So if the PCs become overeager to break out the lightsabers, feel free to remind them that as powerful as they might be, a handful of Force users with lightsabers is no match for the weight of the Imperial military.