[William Tell]

I see nothing in the requirements to suggest that Trump cannot take the oath just prior to noon.

[Arthur McGowan]

Exactly. Nowhere does it say he must already BE President to take the oath, or that the taking of the oath CAUSES him to become President. It is the arrival of Noon that does that.

[Pilsner]

I see nothing in the requirements to suggest that Trump cannot take the oath just prior to noon.

Me neither. In fact, I seen no reason why it could not be taken any time after Congress certifies the Electoral College winner, and we have an official President elect.

But if Trump decides to wait until after noon on Friday, there will be an interval.

[SauronOfMordor]

There’s nothing in the requirements that prevents him from taking the oath the day before (just in case of disruption), then doing it again at noon, just for ceremonial purposes.