You can certainly move the apron edge buckle(s) forward (and remember to move the underapron strap, too). The problem is that, at some point, the underapron starts to show, and it's really obvious.

On the other hand, when you move the buckles back to make it smaller, the fringe edge just covers up a few more pleats, and, unless someone really looks to see that the center back is no longer centered, it's not at all noticeable. And it's _really_ not noticeable if the kilt is pleated to the stripe, because there's no obvious center back.

So, you typically can't make a kilt very much bigger before the underapron starts to show, but you can make it a _lot_ smaller before anyone notices. Whether your underapron will show with a buckle move of 1" depends on where they put the buckles in the first place.

Best of luck!