You don't need to rank for "tinder for names" because I doubt anybody thinks that they need that specific service.
The obvious market is expectant parents and you should be focusing on that, either in terms of forum posting, SEO, or paid advertising.
I would look at your competitors. I searched for "Baby Names" and the #1 result I found was this site:
It's hard to beat the power keywords in the domain name but you should understand how people get to that site, be able to explain fluently why your site is better than that site, etc.