No problem with asking for confirmation.  :) On the 707, the document shows how to load the tanks. You'd start filling the centre tank at 38.000+ lbs of fuel. Any amount below that value goes into the wings only.

Maybe it helps to look at the architecture of the plane in full when it comes to the method of keeping the wings 'heavy' as long as possible, draining the centre tank first.
Reasons are the structural load distribution and CG planning plus movement due to fuel burn. The last part is more of a logical task though and modern planes use their fuel not only for running the engines and cooling stuff, but also for trimming the plane.

A rough view, not being plane-specific. The lift generated opposes the the aircraft's weight. Since your wings are the only structural part of the airplane where that counter-acting force is generated, the rest of the plane has to be supported by them. By this, the same plane with the same overall amount of fuel but now in the fuselage (instead of the wings) causes a bigger structural load on the wings itself and the wing root. You even have to look at the fuel density as the important value is the added weight.

The weight in/on the wings therefore causes a bending moment relief. Lift goes up, weight goes down and you therefore want as much weight where lift is generated and less where having a 'dead' structure in lift terms. By that, the engines on the wings and the fuel within them can lead to a lighter wing structure.

The rear mounted engine planes for example feature more heavy and stiff wings but then allow for an aerodynamically cleaner (wing) design and the better usage of high lift devices. But there's more on the case of course.

Either way, you will find the 'load wings first' policy on many planes. If you wanted to run it the other way around ('load centre first'), the structural setup has to be different and most likely heavier in general. The 727 comes to my mind as an exception. She's running the centre tank equally and doesn't drain it first. If AUX tanks (in the fuselage) were installed, those would go first though.