She accepted the idea of going out for a drink but we didn't talk about when. How to approach it next?

So, after I asked out a girl I like over text to get some drink sometimes after her exam, she answered "Absolutelyyy, we should" but we didn't talk about exact time and date when, as I thought it wouldn't be appropriate as she still have her exam for which she doesn't know when it is (it will be in next few days or so). Did I make a mistake for not giving her date? What should I do next, how to approach her about that drink? Should I just be like "Hey you wanna grab that drink we talked about on X day" or casually ask her when is she free? Thanks in advance!

She accepted the idea of going out for a drink but we didn't talk about when. How to approach it next?
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