Can we use the idiom "now that" when referring to past events?

Question

Please consider the following scenario:

Now that he'd got/gotten the truth, his face enlightened.

I know that now that is an idiom and should be taken as such, and since it may mean since I don't see any impediment in using it.

On the other hand, now, according to the American Heritage of the English Language, definition #3:

3. In the immediate past; very recently: left the room just now.

So, since my sentence refers to a now used in a distant past I wonder if there might be any conflictual semantic in it.

Note: in my language such example is perfectly valid.

Answer 1

*Now that" is a phrase used by someone who is telling a story (broadly construed, not necessarily an author; it could be anyone, in casual conversation, say) and it establishes a reference time or a reference context.

I came in out of the storm and took off my boots and heavy coat, and put on the kettle for a cup of tea. Now that I was indoors and out of the bitter cold, a cup of tea in my hand, it gave me a cozy feeling to look out the window at the snow.

In this little narrative, "now" refers to a context in the past, as far as the listener is concerned, but it was the present condition of the "I" in the story. You can think of it as an invitation to the listener to enter the speaker's frame of reference. Now is deictic.

It can also be used to establish a reference time/reference context in conversation:

Now that you've finished your degree, what do you plan to do?