If EUA runs as scheduled, some coach seats will probably open up at 5-6 days, some more at 3-4 days, the rest at 24 hours. But the seats that open up will mostly be premium seats, and, if you're not elite, they won't do you any good til the 24 hour mark, when the remaining premium seats are up for grabs.

Since it only takes a couple of minutes to try to get seats online, I'd do it every day in the week before the flight. Try first thing in the morning, or late at night if you stay up past midnight.