Set Start Measure Number to 0 (Zero)
I did a search for "Start Measure Number to 0 (Zero)" and couldn't find anything mentioned in the forum and google search. After stumbling around in Format\Styles..., I finally selected the first measure and right clicked and I came across Measure Properties\Add to measure number: Here I inputted "-1" and this changed the first measure to zero. While in Page view, I selected the "0" measure number and made it in visible in the Inspector Menu (F8) and in addition I changed the Frame: from No Frame to Circle then clicked the "S" button to the right to "Set as style" so that "In every system" (refer to Format\Styles...\Measure numbers\Every system is selected) a circled measure number will be indicated.
I was transcribing a classical piece and noticed the first measure was set to zero. Hopefully this will be helpful for some needing to do something similar.