How are you planning to mention it? In the resume? That's it?
I think it is safe to state that you are an "Accounting Certificate xxx candidate" - this indicates that you are in process of getting one.
If you want to use it in your application essays, If there is an optional essay for your school, you may want to state that there.
P.S. You do have a very good question. Schools often will not accept any additional info/data after the deadline. However, this is a tricky question since your exam is coming BEFORE the deadline; it is just that the confirmation is coming after.
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