The question we have is the cabinets on the wall with the pantry will be fitted between an existing wall and the new wall of the new pantry. We didn't want to add a filler piece as this would take away from the balance of the cabinets. The base units we're not concerned with as the fridge is on one end and the space for the fridge can accomodate any slight variations in width. The issue is with the wall cabinets as they are solid between the existing and new wall.
We're debating on building the pantry first and "hoping" we got the dimensions correct or installing the wall cabinets and then building up against them. We're worried having the cabinet up we won't be able to properly finish that side of the pantry wall or we may accidentally damage the last cabinet. We'd rather have all the walls finished before mounting the cabinets. We also thought about building the wall and possibly the whole pantry and not attaching it to the back wall until we have the cabinets delivered and then work out the exact measurement (or mount them and then take that last unit down).
We're kind of new to this so we're totally open to suggestions not just for the pantry wall but for building the pantry itself.