I would do your relic now, while you are leveling jobs to 60 since you will have to do a lot of lower level dungeons as part of your book, you might as well get some xp to use. Also if you do daily roulette, it gives you those poetic tomes that you can use to purchase books you need to finish your relic. This is not something you want to do all at once, it is better to do it a little at a time.