I used the words "film" and "screenwriter". I ended up finding big accounts in the industry as the first results. But then I switched over to latest posts with these search results and I found many smaller companies and individuals who are linked to the industry as well.
I created 2 lists with both of the things I searched for. One list was for film and I wanted that to be a bot more broad. Then I made a list for screenwriters so I could have a narrowed down list with a group of people with a specific niche.
The best time to post on twitter is between 9 am and 3 pm. That hits most people's business hours and that also includes enough time for lunch hour and possibly breaks. That's when people could be most active on twitter.