I'm not sure it's in your best interest to specify that the movie should use multiple supers. Remember, a screenplay is just the blueprint for a movie. You only need to include the details the rest of the crew need to agree on to tell the story. Everything else can and should be left to the director and the rest of the filmmakers so that the final movie is ...
Just write what you mean clearly and expect intelligent people to understand it. In a recent script I indicated I wanted various lines spoken while they appeared as text on the screen. I wrote that. It was clearly signposted. People understand it.
Don't use abbreviations before you explain them. For example, above you say 'multiple supers' and I didn't know ...
Pick a phrase from your novel that is significant.
'The Day Before'
Worried it doesn't stand out? Try restructuring it to make it slightly more unique - and make sure that still fits.
'Before The Day'?
Bend your perspective.
Run the words through www.thesaurus.com and see if something new pops.
'Auld Lang Syne'?
Make something up