@cjhsa,
You do realize that before he can be impeached, he has to be sworn in?
He is in a rather curious position, he is not yet the President, and wont be till he gets sworn in, but he isnt really a Senator anymore either.
He still holds the title "Senator", but since he is the President-elect, he cant perform his duties as a Senator.
So, since you know so little about how the system actually works, may I suggest you do some reading about the subject and educate yourself.