From my experience its going to be a more than a week, but its possible less than 8, I agree. There is some backend stuff thats a bit more complex than avg chat app, but nothing crazy. I would rather overestimate the time then tell someone it is going to be simple. Also both iOS and Android versions would have to be released to really test it (how it works makes a web version on mobile not possible).

If you know a person/people with skills who might be interested, pls let me know, thanks!