I see your point, RobertJ. Wedged into a narrow and very specific time frame, the original might certainly be commonly heard. The OP did ask if it was correct. I stand by my opinion that it is not actually correct and would be best if slightly altered.
Ju: My #1 suggestion is closest to the original. In spoken English, we have would be contracted to we've and, when followed by a word that begins with the same mouth configuration (finished), the "v" of we've would get rather lost (would not be voiced), so it would quite likely sound like we finished...