If you can't be there early enough for sign up, can you get somebody else to put your name on the list for you? I'm coming from out of town & won't be able to get in until the morning of auditions, so no way I can be there at the crack of dawn, but I have a friend who will be there & said she would sign me up. We are non-equity if that matters.
Yes, since you are non-Equity, your friend can sign you up. Try not to get there too late, though - you never know when they might call you in! If you were Equity, you would have to be there in person, with your Equity card. Good luck!