Past perfect and using before/after

My friend and I are having a debate about the following sentence and what to slot into the gap:

______ we had finished the course, we received certificates. (Before/After)

To me it sounds correct to use either before/after in the sentence, like this:

"After we had finished the course, we received certificates". (We finished the course and then received certificates after that).

"Before we had finished the course, we received certificates". (We received certificates before the end of the course).

My friend, however, argues that the action expressed in the past perfect ("had finished") must always be the preceding action, followed by the past simple ("received certificates") and so it is ungrammatical to use "before" here.

Which interpretation of the grammar is correct here?

Solution 1:

Both are fine grammatically, and if anything before is the one where the the past perfect is the more useful.

Consider:

The desert course was a simple panna cotta. Before we had finished the course, we received certificates.

As the first sentence has set up the circumstances of the course, the perfect "had finished" gives us a period with an end in the past, and the before places the simple "we received certificates" within that period, just as after would place it subsequently.

It's not merely grammatical, but its perfectly fine in other regards too.