I googled and couldn’t find an answer although I think I found it. I’ve been reading Soul Love by Sanaya Roman (again). This book has so many good reminders! On page 203 she writes… “There are millions of people who are working to bring about an awakened humanity. I will call these people lightworkers.” Sanaya (I ❤ you) published this book in 1997. I wonder if the word was used before then. If you have information, feel free to comment.