I upgraded to a Samsung Trender on 11-2. I picked it up on 7. on the 19th decided on a different phone. they said it was activated on the 3rd.
You need the information (ESN, IMEI, HEX or DEC) located beneath the battery to have your phone activated. So unless you have the information needed, you won't be able to activate your phone. Besides, you picked up your phone on the 7th so it's impossible for you to activate it on the 3rd.