Most alterations have a domino affect. Which is why we do dresses in a certain order with a fitting for each step.
At the first fitting we look at everything from the waist up. Sides, straps, and bra cups are done at this fitting.
The second fitting is for the hem.
The third fitting is the for the bustle.
The fourth fitting is for the final fitting. Make sure everything is perfect. Teaching your attendant how to secure the bustle and/or corset the dress is also done at this time.