Only need to gavel in 86,398 more times and they’ll be back on track.

Fun fact: The House rules require the speaker to take the chair ‘precisely’ at the hour to which it last adjourned. The Senate has no such rule.

Is the beginning of the daily session counted from when the speaker/president takes the chair, or when they call the chamber to order?

The latter, I think. In the Senate, the presiding officer often sits in the chair for some time before calling the Senate to order.

And then is it when they first start speaking? Finish the word “order?” Tap the gavel?

Sometimes they don’t have an opening line, so I guess it must be when they tap the gavel.