If they've only been queenless for 8 days, and there is brood in the box, you
shouldn't have to worry about laying workers.  In my experience, laying
workers begin to develop only after there is no more brood.  At the minimum,
it takes 2 weeks for a worker's ovaries to develop (according to _ABC and XYZ
of Bee Culture_ ).
 
You should check for queen cells before you install the new queen, and
destroy them.  You don't want an emergency queen to emerge and possibly kill
your nice new queen.
 
Emergency queens (once again, in my experience) are usually puny and less
productive.  They may be acceptable in a pinch, but I don't let them live
long.
 
Good luck!
  Shawna