i got quite large implants about a yr and a half ago.(before any babies) i was measuring 12F. so you can imagine how huge they got when i got pregnant lol. iv stopped BF so they are back to almost normal. but i would consider a lift probably after next baby.
FYI if you're interested in getting a lift aswell, you may find just getting the implants will actually get you the result you want, so you wont need lift. (unless of course you have large breast to start with.