Shadowbringers Gathering + Crafting Quests

Those quests that we do from the Crsytalline Mean, should I save those for level 80? Will they give white scripts instead of yellow if I do?

Do them straight away, they'll give tones of exp - and no, you wont get white scrips at level 80, you'll only lose out on 3-4 levels per questline...

Alternatively you can wait till level 75-76 to do them, when the cost of stuff for levequests are higher, and knock out the last few levels with the quests, depending on the profession. Just don't wait too long, you don't want to waste the xp from these quests, and as mentioned above, there are no extra rewards for doing them at 80.

Thank you both.

Also worth noting that they give a fixed exp, not a percentage of your current level. So there's no extra exp for a partial turn-in to level up, then turning in the rest.

I would also go a step further - doing these quests early give scrip which can be exchanged for gathering/crafting gear better than anything you will get before level 80 otherwise. It is definitely going to make your life a lot easier if you do the quests when you can.

They gives TONS of exp. Also, use them as yellow scripts. Each master recipes book costs 1200 yellow scrips. I was able to buy over half my master books with these quests.

I used these to level my Fisher, Blacksmith, and Armourer. I'm going to use the last one to work on my Carpenter for its last two levels.
Like others have said, the scrips they give are well worth it. Yellow crafter scrips for master tomes (or materia, if you get all of the tomes), and gatherer scrips for regional folklore tokens is a godsend.