to cause something to initiate/start
Also: keep/set/start the ball rolling
Let’s get the ball rolling and tidy up the mess, we have a few hours before the guests arrive.
start / set / get the ball rolling
to do something that starts an activity, or to start doing something in order to encourage other people to do the same:
I decided to set the ball rolling and got up to dance.
Cambridge Advanced Learner's Dictionary - 4th Edition
© Cambridge University Press 2013