So, my story with the evo and new premium plan.
Stayed up late ~3.30am last night/this morning hoping I would be able to put it on my plan through the sprint website. This failed after multiple attempts and then the website went down and I couldn't even log in.
Got up this morning, went to the Sprint store (corporate) - looked at some cases for my evo, talked to a nice guy who knew nothing about the SERO Premium plan and said to me "I'm not going to mess with your account because it will only screw you in the end". Fine with me... He says to call Customer Service.
I all CS and get through immediately (this is about 1:15pm eastern time) to a man who knew exactly what he was doing. The whole process took ~4-5 mins TOPS. He switched over my plan, said to power on the EVO and BAM! I could make calls/surf the web as soon as it activated.
TLDR - Call up CS and have them do it for you. If you already have the phone - say you want to upgrade your plan FIRST then tell them you are just doing a phone switch.
Now i'm a happy guy with a rooted and freshly installed new ROM on my EVO