@GrandmaLilly - congratulations on publishing your first course. Now the real work actually begins - getting your first students. I suggest you join the Published Instructor Club ASAP. Take a look at the marketing thread as there are excellent tips to get you started on the right track today.
If you already have an FB Group dedicated to what you are teaching then yes put some discounted coupons into it to generate sales. General FB marketing - I have never lost money however have never found it really effective either. Break-even and hopefully they have gone on and purchased other courses - discount coupons once per month through my FB Group, Pinterest, Instagram and YT all bring in a dribble of students for me.
Sharon Ramel Spiritual Guide, Shaman, Priestess of the Blue Rose