A typical crafting session will have you alternating between several (sometimes all) of your crafting classes, as they make stuff for each other. So it helps if you keep them all pretty close to the same level. (That has a second advantage as well, that they can all share gear if they're at or near the same level.) So I don't recommend even thinking of it in terms of leveling one and then another, but simply leveling the whole set, with particular emphasis on catching up any that have fallen a little behind the others.