short, sweet and simple story.
For a 1h visual novel, which, by itself, means a certain set of complications.
Sure, you can ignore those complications, but...well, quality will most surely be harmed.
To begin with, even if it's a short thing, it requires a document that couldn't be done properly in less than a month. Time only increases if one decides to add branching choices and different endings.
This is not a huge, epic project, but refering at it as "short and simple" it's a bit of an understatement. No sarcasm here, it's not much of a hassle, but can prove bothersome.
Part of the problems would be opening, developing and wrapping up a story in one hour worth of
text. If doing that in three minutes of movie is not easy, when you add a written factor to it, I wouldn't say it solves any problem.
"But novels..." Yes, but this is not a novel, now is it?
Overall, if you can get yourself someone who knows of continuity and (basic) pacing, it's not going to be any trouble. I'm assuming the artwork is already done. And if I'm correct and all that's left is putting art and text together, a month of deadline seems actually reasonable. If I'm wrong, then quite the contrary.
TL;DR - Get someone who can keep pacing proper and make the VN feel cohesive. If the artwork is done, 1 month is good. If not, maybe not so much.
For the moment, I can only wish you good luck. I'm having dealings of my own currently. Still, if at some point this proposal comes up again, I might want to pick it up.
Also: Details feel murky. I can't tell if you're interested on developing something yourself or if this is little more than a showcase for an engine. In any case, take my two pennies. They are worth...well, two pennies.