It's best to work on both at the same time.
I use the best birds I have with the color pattern genes I need.
If you focus on just the trait you want and not type then when you get the trait locked in but the type is bad you'll have to go back to a bird with type and that sets you back on the trait.
It's a balancing act.
You can't let go of one for the other unless you're prepared to take a step backwards.
Sometimes you just have to though.
I've scrapped whole projects because the type wasn't there or there were too many faults.
The MF is a good example. I had MF patterned birds but they were to much of a mess to fix.
I used the best one I had and bred it to my best buff rooster. Now I'm fighting to get all the needed genes back in one bird.