As I said in the Galadriel thread, she would not be the only person who realizes Feanor started that battle unprovoked. Finarfin and his sons probably figure out the exact same thing, very quickly, and it's probably their first guess as soon as they come upon the aftermath of the battle. And probably many other Noldor will figure this out, too.
Finarfin should start arguing for return now, saying that the whole enterprise is marred with evil and that Feanor doesn't deserve their allegiance. I think many of Fingolfin's host will start to be swayed already, and some will already completely want to return.
I don't get the impression, from Tolkien's texts, that individuals returning to Valinor was viewed as an option. It looks more like the whole host of Fingolfin was engaged in a debate about whether they should continue or turn back, as a group. So that those who already want very much to turn back don't feel that they can, until they convince enough others to go with them, and/or Finarfin goes back with them. But he isn't likely to turn back until it's finally clear he cannot possibly persuade any of his family to go back with him.
The whole situation will be horribly tragic. Families will be torn apart. There are already families who separated at the start of the rebellion, and probably several who are split up between Feanor's and Fingolfin's camps. People will be reluctant to part from those family who still remain together, and this is going to sway their decisions to go on or go back. This problem should come up now, as Fingolfin's host start to debate what to do next. In the end, I think some will turn back who want to go on, and some will go on who want to turn back, only to stay with their family, lovers, or very close friends. Breaking apart families (exemplified by the house of Finwe tearing apart) is a way to heighten the sense of horrible loss and tragedy in the Rebellion, on top of the Kinslaying. It's also a way to get viewers back into the Noldorin point of view, after the Beleriand episodes.