Brassard's advice, at any rate, is to do exactly that : "If you have difficulties with a bigger size dilator, wait before you are comfortable with this one before using a bigger size. You can go back to a smaller size and increase the frequency for a few days."
Width is a question of stretching, and can be regained; lost depth cannot always be recovered, so that's the priority. Which means that if it's a choice between maintaining depth with a narrower dilator and risking depth because the larger one won't go in, it's wise to drop down to the narrower dilator for a bit.
As always, your surgeon's own advice takes precedence over any suggestions from the internet, but presumably if you had a clear answer from the surgeon right now you wouldn't be asking.