Ours have always occured before leaving the dock; not during sailaway.
I thought the rule was within 24 hours of sailing to have the drill although the only time we had muster drill on second day was when we overnighted one time in Hong Kong and another time in Venice.
"Carpe diem quam minimum credula postero"
Seven Seas Explorer - Miami - Venice - Mar 2017
Silverseas Explorer - Arctic - Aug 2017
Seven Seas Voyager - Rome to Beijing - Oct 2017
Seven Seas Mariner - Lima to Buenos Aires - Jan 2018
Silverseas Explorer - Siberia - Jul 2018
Seven Seas Mariner - Australia Circumnavigation - Dec 2018