NFL Owners Approve Modified Injured Reserve Rule

Here's what I don't understand. Let's say you have two players hurt in week 1.

Must you designate one of them the marquee player immediately?

Or can you wait to see which gets healthy quicker, before deciding who is the one to return later in the season?

that was going to be my next question. i would assume that the team would have until the player starts practicing (if i understand correctly the marquee player cannot practice for 6 out of the 8 weeks on IR), to notify the league of who you are going to use the marquee on. but then again this is the nfl, so nothing is logical.