So ideally you dont want to be capped on poetics so that you can continue earning more. The main uses of Poetics are buying older cap-level gear(so 50/60/70), and working on relic weapons. If you arent far enough into HW to have access to the level 60 vendor, it might not be a bad idea to buy a few extra pieces of top tier level 50 gear for other classes you would like to play if you get close to having 2000. If not, it isnt the end of the world to lose a few tomes here and there to being capped. As the others noted, only the highest tier(endgame) tome comes with the weekly earning cap, with both lower tier ones being uncapped for what you can earn(all 3 do have carrying caps however).

Side note: If you are that far ahead of the MSQ for levels it might not hurt to grab a 2nd(3rd, etc) class to give some of the experience to. If you are on the free trial(or just have the starter version of the game) this might mean waiting until you can open up the HW jobs so the leveling isnt as much. If you are on complete version(or starter + shadowbringers) you could unlock samurai or red mage in ul dah, as both start at level 50 and could begin absorbing extra exp immediately.