If a person for whatever reason has to eat and drink on Tisha B’Av that comes out on Sunday, and they know this ahead of time, when should they make havdallah on a cos? Should they make Motzei Shabbos like normally (however omit the other parts of havdallah that are omitted when someone would normally make havdallah on Sunday night after Tisha B’Av.) Should they make havdallah (on cos) only right before they will eat or drink. Or Should they wait and make havdallah (on a cos) Sunday night like everyone else?
Whenever they are ready to eat they should make havdalla. They should say ony hagefen and birkas havdala. The bracha on besamim is not said, and the bracha on fire is made right at the onset of Tisha Bav.