When it first appears it will look more like a large star or comet.
Only the last two weeks of its approach will it visually get larger to the viewer; @ 7 days out it is half the size of the Moon. @ 2 days out it is 3.4 times the Moon diameter. @ 0 days out it is 30-70 times the Moon diameter depending how close it passes to Earth.
Gill Broussard - Astronomer