This may not be what you want to hear but you MUST go try to sell it prior to launching it. I've launched a couple serviced based businesses before and the difference between success and failure is having around 4-5 PAID customers prior to the official launch day.

Do get 4-5 I would reach out directly to LinkedIn contacts you think would be good fits and pitch them the idea. Try to avoid friends and family as much as possible.

Also, remember that anything but a hard yes is a hard no. What does that mean? It means if someone says 'how much is it so I can sign up' or 'can I sign up now' that's a yes. If someone says 'yeah, sounds like a good idea' or 'wow, some people would really love that', those are no's. Do your best to get 4-5 yes's prior to launching. That way you know your idea is validated and maybe you can get some good testimonials for marketing purposes.

Good luck!