Generally speaking, in FF8, it's better to avoid levelling up and refine strong magic for junctioning. Enemies level up with you, after all, so there's just about no reason to gain levels because low level enemies + awesome junctions on your characters > high level enemies + awesome junctions on your characters.

But monsters will have better magic to draw from them as you level up. So it depends on whether you like to get your magic by drawing in battle or refining.

Personally, I like to fight monsters as they come. I still like to learn Enc-None almost straight away, of course, but I don't make any special effort to avoid levelling up before I get it. I will, however, try to be efficient and draw 100 of anything from everything whenever I see it.

To answer your question. I never grind in FF8 ('cept Cactuar grinding for AP)