Era realms (1-60) do not allow you to move to the TBC/Wrath realms and will never be upgraded to TBC. The only way is start on TBC realms, get to 70, then wait for them to change to Wrath realms and level to 80.
Sorry but you are a few years late to start on Vanilla, then play a max level for a year, then upgrade to TBC, play for a year, etc.
Make sure you scout out the realm you want to choose first and don’t start on a realm in this list. For approximate populations look at ironforge.pro.