Ok, to start with it's materia. No L, just like the christmas song.

Anyway, as far as how long it takes to fully spiritbind something, that depends on a number of factors. Spiritbind is gained by doing actions that would gain you xp, namely killing monsters, making items, and gathering items of a sufficient level. From what I've heard, how much xp these give is irrelevant, so it's less "Gain X amount of XP while wearing this" and more "Kill X monsters, craft X items, or gather X items."

There are a number of items that increase your "Spiritbind" stat, these will make you spiritbind stuff faster.

High-quality items spiritbind faster. Items with materia in them (throw in junk materia nobody uses, like resistance ones) spiritbind faster also. HQ items with materia in them spiritbind fastest of all.