Do you still collect a noble if the day ends?
I concur with Pat's answer - I have my copy of the rules in front of me, so can quote chapter and verse!


  Play continues in this manner until there are no nobles left in line
  at the start of someone's turn.  That day is then over and a new day
  begins. ... The player to the left of the person who started the
  previous day is the first player for the new day.


Essentially, emptying the line of nobles does not end the day, nor is the line immediately refilled with nobles.  The day ends at the start of the next player's turn, and as Pat says, a new player will be selected to be start player and thus the first to collect a noble.