I just started as a class 8 tech, (after 4 years hobbying and 23 years owning trucks) and the first things I bought were a 33mm 3/4 drive impact, and a 3/4" Drive Budd Wheel Impact Socket 1-1/2" X 13/16", a 1/2" ratchet at least 24" long, filter wrenches, yes, but most truck shops with a lube/service pit will have some, jacks / stands the shop will definatly have them, run away from a shop that doesnt. Be ready to do a lot of tires, a lot of greasy nasty lube/service work.
If you do wheel seals you might want a travel dial and magnet mount for it (if you dont have one, I use the same one I use on ring & pinions), also there are a lot of good tire tools that work better than a gold-bar or the standard spoons, check out Ken-tool.
Other than that the basics are good, just be ready to buy everything a little larger, wrenches up to 2", and good pry-bars. the wheel end sockets at 2 1/2" and up the shop should have as well as seal drivers/setters, they take up way too much space for a shop to expect each tech to have their own set.
Oh, and one edit here, if you dont have one already, a service cart is a must, you cant roll a huge box across the bays and running back and forth gets old very fast, a good cart (I use the 5 drawer HF cart) will save you a TON of time and trouble.