When should the expansion hit? The first and foremost thing come into your mind will surly be the different location of horde and alliance. It's not horde and alliance starting in two different places. It is horde and alliance each starting two different places, that's the horde and allies will have different starting zones in the expansion, apparently located on opposite sides of Northrend. This is because Blizzard remembers hellag laginsula from launch week of the first expansion. Both the horde and the alliance will have the choice between starting in the southwestern or the southeastern end of Northrend.
All of these will halve crowds into two parts which means those will spread everyone out over two entry zones instead of one (Hellfire Peninsula), thus scattering all the crowds which will help people get their direction and avoid the bustling of players.
  Ganking could not be classified as a problem in early TBC. It just calls for people's little attention and careful choice of which of the 4 players standing on the mob spawn point that happens to be lucky enough to tag it. Not many are wasting time on PvP because that would just mean you definitely are not the one getting to tag the mob.
  We can resolve the problem of overcrowding by leveling our grades to 70 so as to avoid it. Managing to deal with crowds can ensure you enough time and energy to go around.
   I'm sure approximately 1.000.000 rogues equipped in full PvP epics with monster enchants etc will sneak across the continent first chance they get to gank as many "lowbie" 70s as they can as the unsuspecting players on the opposite faction is trying to do the starter quests; clearing out mines, gathering plump wings and digging through boar poop and whatnot.
Ganking wasn't actually bad with the release of TBC; it was as though there was an unspoken truce between factions at the release of TBC. Or at least it was like that on my server (PvP). Most people are too focused on leveling to be ganking people. You can choose to level your 70 right away honestly, because as soon as the leveling rush dies down, you're going to be hunted like the lowbie you are.
   As I have mentioned, when the release comes a lot of servers head to the forums and post truces, basically no ganking just leveling, of course you still get it, but the majority wont because they are more focused on leveling than spending time with what they've been doing from the last year as 70.
Also, if you're not on a PvP server you are safe, and I am not going to level the Dead knight first for various reasons.
   Basically, when I got to 50 TBC had been released (second character) and I had a problem, when going through 60-70 majority had already got to 70 and were not interested in 63 Dungeons, I.E Steam-vault, Blood Furnace, Hellfire Ramparts, so I had one hell of a job finding a party for them, and it got worse, when I got to 70 everybody had done the instances, and I think it took me a week to do around 15 Shadow Labyrinth runs, I had cases where I had been trying to get a party for 3 hours, it just drove me nuts. So basically if you do level with everyone else your gaining the ability of finding parties a lot easier, parties for group quests a lot easier and wait for the the price of the occasional gank.
With powerleveling tips in mind, you should to get a start and learning how to power level yourself in World of Warcraft.