Some artists only put the background paper in the plastic bag after they did artworks during the event. There’s nothing wrong but it reducing the quantities you are going to produce within the booking hour, that could be one way to ‘kill the time’, but I think that not so professional.
Except the background paper was given by the event organizer which printed with their event logos last minutes when I reach the working place, otherwise I always prepare them by myself before I go to the events.
The paper for me to do the silhouette or side profile cutting, usually in 1/4 of A4 or roughly about our palm size, so do the background paper.Of course I also prepared some A5 size background and the cutting paper for those cutting in couples. .
Not every type of cut-out of the silhouette can be use, like the couples design, due to it needed to cut through the paper, hence it will be throwing away.