You should test the starting gravity, and check again when you are finished. It's not necessary to check in the middle unless you suspect it is stuck, or are just curious.
Maybe that's not the right question. Should I be testing daily while this stuff is in the primary? (I think that's right)
The yeast was pitched 2 days ago.
Yeah give it about a week and a half to two weeks then take a hydrometer reading. In another couple days take another one. If they are the same then it's done. If it changes go a few more days then check again.