Worried about size

I am almost 3 weeks post op and I just tried to size myself and I'm measuring as a 36G.... Please tell me I'll go down to a D? I was really hoping I'd be able to wear normal bras off the shelf. I started at a 36I with some spillage. They took 690g from one and 600 from the other. I love the look of them and I feel like they shot my body a lot better but I'm terrified I won't go down to the size I wanted. Anyone else experience going down much more after 3 weeks post op? Surgeon said I'd go down about 20% when I went to my 10 days post op appointment but idk what 20% would be.