Did you know that you can use buttonhole elastic (BHE) for the gussets on the TWIST? Using small buttons sewn at each end of the casing and BHE you can make your gussets on the OS TWIST totally adjustable for your growing baby. You can find diaper making BHE here in Serena's Assunta Store.
You can also adjust the elastic by undoing the tack down stitches at each end of the casing and loosening or tightening your elastic. This is also how you would change out the elastic should you need to replace it.