No i feel if it has slots it should be filled with materia, i started putting materia into my jewerly and armor at level 15, to me it helps im a gladiator and all the added parry and vit i added to my gear made dungeons pretty easy, i fought ifirt and he barely hurt me. I juat really enjoy crafting and materia melding i find it a fun part of the game, i know you can beat the main story with just quest gear and droped gear, plus pink droped gear is on par with HQ melded gear. For me i see no point in waiting till level 50 to add materia, for me i wanna use every item i can craft out in the battle feild insttead of just ruahing a crafting class to level 50, and if you start early you will have all the gear you need to turn into materia. Thats my two cents on materia.
Beastmaster ~<3 Cant wait.
Gold smithing till the day i die!