Here's how I do my '29 roadster top. Unsnap the fasteners from the back and side curtains, and pull them through towards the inside of the car. Unfasten the front fasteners from the windshield and fold down the top carefully, being sure (as Charlie says) to not pinch the fabric in the mechanism. Straighten out places where the fabric might not have folded up properly (happens on the ends mostly). It should be as flat as it gets, at this point, and the boot should fit. A lot of "shoulds" here, I know!