Example: On Monday, a Judge orders a party to file and serve a document within (or no later than) five days. The time period begins on Monday, so the first day to count is Tuesday. The second, third, and fourth days are Wednesday, Thursday, and Friday. The fifth day is Saturday, so the time period rolls over to the next business day, which is Monday. The deadline is Monday (or Tuesday if Monday is a Federal holiday).
13 C.F.R. §134.202