You're missing the point of the original post suggesting a pre-made roux.
If this is your first time making a gumbo feel free to use a pre-made roux. Being the foundation of a good gumbo if you screw this up the gumbo will taste terrible.
Feel free to give her your pre-made roux or she can use Doguet's roux in the jar -- same difference.
Having done both, Mrs. Douget's can't be beat. 4951