Great question! Whenever we recommend compression garments after surgery (all liposuction patients and many "lift or tighten" operations), we provide them at the time of surgery, and my nursing staff has a huge selection of sizes and types of garment in stock. Since we often include bandages and pads as part of the post-op care, we feel it is our responsibility to select the best "fit" for the patient, rather than having them try to "guess" what may be necessary.
Too tight is cutting off circulation, or acting as a tourniquet.
Taking off compression too early is a huge NO-NO! Not only can the surgical areas fill with blood or fluid, leading to increased scarring, swelling, ripples, dents, and other undesired contour deformities, once the garment is off, swelling increases IMMEDIATELY, and the patient finds that they cannot get the garment back on! (Yes, even for a super-quick shower, or laundry session for the garment!) Then we get a phone call from the anxious patient who wants to know what to do. Unfortunately, the answer is too late: "Don't remove the garment for any reason!"
So even if the garment is bloody, has fluid leakage on it, or if you inadvertently pee on your garment (or worse), leave it on! Clean it as best you can, but leave it on. After one week, we remove the garment (and any sutures), replace the pads, and put it right back on (since the swelling has had time to go down a bit). You may now remove the garment to shower yourself and launder the garment, but will continue to wear it for a total of about 3 weeks (or until all bruising is gone).
After that, complete resolution of swelling takes 4-6 months or more, and a compression garment of your own choosing (like a Spanx or equivalent) will help your shape and swelling, but is not required. Follow your surgeon's recommendations, for it is he or she you will go to if your results are not what you wanted, and perhaps it may have been your fault if you take off the garment too soon, or get the wrong size. Good luck and best wishes!