Thanks!
I believe you can pre-order tomorrow and jump right in with the early access benefits
I was told that all you need is the Early Access code to sign on tomorrow when it starts. The actual time it starts is a bit vague, but seems to be 7am EST. Gamestop preorders will mail an email tomorrow morning which contains your preaccess codes. Order direct from Bethesda, and I think Steam, and you get your preacess code right after the order is complete. Now GameStop said their preacess codes will not be released until 7am EST. I think this is standard for all dealers. There is some technicality involving the difference between a online download versus a hard copy purchase, but I can't imagine it will be any different.
Now, being in Beta, I have already downloaded and updated the client without the Early Access code, so maybe Beta users automatically get Early Access???