Hi! I remember feeling anxious about sitting my AS French speaking exam last year, so I understand how you feel!
My tips would be to
breathe - a bit of an understatement considering we naturally do that anyway, but taking your time to express your ideas coherently is better than panicking and saying your words in a rush when you sit the exam! I know it is easier said than done, but try to regard your exam as an ordinary conversation - albeit with a small recorder and an examiner whom you've never met before in your life (I'm assuming that an examiner outside of your school is conducting the exam?).
Try to refer to contextual points whenever possible so you can maximise those marks based on knowledge of French-speaking countries. Even name-dropping statistics (or, if you can't remember particular number, refer to the agencies who gathered the figures, e.g. Insee) counts, and shows your breadth of knowledge regarding the Francophonie world.
Ahead of your exam, just practice preparing speaking cards in timed conditions (I assume you have 15 minutes to prepare 2 of them - far more generous than the 5 minutes I will have in my A2 exam next month!) and focus on making key points, using vocabulary which is specific to your topic. For example, le concubinage et l'union libre for the topic on families.
Personally, my speaking exam was alright last year, although I came a bit unstuck with being forced to choose between two speaking cards from a particular topic which I didn't really like - but I recommend that you select your cards based on your ease with finding contextual points linked to French-speaking countries to make things significantly easier!
Best of luck with your exam on Monday (and don't forget to give yourself a well-deserved break after you've done it)!