I do concentrate in a french press as well. Usually about a cup of coarse ground beans. Then I cut it roughly 50% with water when I drink it.
I find it works faster to leave it out overnight then put it in the fridge the next morning. Seems to take longer to finish if I put it in the fridge right away.
My wife doesn't drink coffee so smaller amounts work for me. That looks like a great solution for a small office/business setting. Prepare it before leaving work and it's ready for consumption the next day!