Should I work with it?

I know Maple Warrior adds a % of stats. I'm guessing it is most important to get that to affect your leveling? I just don't see why else you would get that before at least level 8-10 genesis.

Because your magic will be influenced alot by the amount of int you have, it is very beneficial to have MW up to 9 as soon as possible. That way you know how much magic you will have with your current equips and level 9 MW. By knowing that you can also know what level Genesis you need to (x) hit KO the monsters you train on.
The higher the amount on INT on a level up, the more Mp you will gain too, so its usefull to gain MW 9 soon for that as well.