Hi @thesimpson5 I think you are on the right track. Even though I have always had the opposite issue of having to go out a size over going in a size. The method is just the same, gradually take the line into the 4 from the waist. Although, because it is a pleated style there will be volume when sitting etc as part of the design, you could try just going with the 6 all the way down to check if you really need to take it in.
I would be more inclined to do this adjustment on something like the wrap skirt but of course this is your garment.
So, do what you suggest, you are on the right track and if you find that it doesn’t turn out the way you thought, just go with the 6 all the way through.
Hope this helps.
Tamara