Rental-like web app

hello everyone,
I would like to launch a rental app as quickly as possible how can I do it?

My background is dev, but I don't want to waste time before getting the idea validated by the market.
I was looking for CMS in Nodejs, but everything seems to take time, so I found WP Rentals. What do you guys think?

Also does anyone have any ideas on growth?
I'm wondering for example when I could already consider contacting an investor (number of subscribers/visits, ec...).
Any advice is welcome :)