Ua check in and how it relates to boarding priority

I'm traveling ZED on UA tomorrow, and wonder if the time you check in affects your boarding priority within your priority classification. I know that AS bases priority on date of hire. Can you check in online on a zed e-ticket, or do you need to be at airport.
thanks

Basically, if there are any people in your priority (ZEDs) with your seniority, TOC becomes the tiebreaker. I wouldn't worry about it too much. I'd be shocked if there are any ZEDs at all. Your flights are still looking pretty decent, btw. 24 seats, you're #7-8 on the list to IAH. Then LFT flights have 4, 5, 8, 3, and 8 seats, and you're the only nonrevs all day on that route (not counting the two on the flight before your arrival)

Edit: just saw your other question. You should be able to check in online if you're eticketed. Paper ticket is another story, but UA employees can check in online just fine. PM me if you have any problems.