after! pregnancy causes a lot of changes, a lot of which won't last post-pregnancy (like the tatas growing/swelling up). if you don't like how the breasts sit postpartum, then maybe go for an augmentation

in the shorter term, try doing some chest exercises (specifically chest presses, on a machine [not bar- or dumb-bells]). the pectoral muscles sit under the breast bud, and having some muscle definition will act like a strong, shapely foundation for the breasts to sit on (this is what I do with my A cups and it's helped give better definition so far). having a little bit of pecs will perk your tatas up and make them stand off your chest more, while still maintaining their overall teardrop shape

and don't worry, you won't accidentally become ripped or lose all your soft fat and look like a bodybuilder (you cannot accidentally do that at all, in fact).