“That’s the “magic date” for me..., because then the rules change...”
What do you mean when you say the rules change?
You asked — “What do you mean when you say the rules change?”
You can do things legally (at least, theoretically, if not in “practice” so far) with Obama before he is in office. Once he is in office, then separation of powers (between the branches of government) are relevant (he being in one of those branches).
If he were to be removed, Congress is the one that has been assigned the power to remove him through the Impeachment and Trial process (per the Constitution). The Supreme Court cannot do anything to remove him from office (the Constitution doesn’t give the power to them and has specifically given it to Congress) — and if asked to, they would defer to Congress to do its duty.
But, we know how well that worked with Clinton...