This is a bit strange question. I was wondering is there a named concept that ease of first use/trial is critical for winning new users and conversion. I'm referring to products/apps/services rather than websites and the aspect how fast and easy it is to try something and see value. I wanted to learn more about this but all I found was about websites.
Yes, often called "First Time User Experience (FTUE)", "Out of Box Experience (OOBE)" or "Unboxing".
There's lots of good articles out there depending on whether you're developing a website, mobile app or something else.
Some good first guidelines are:
- Give users a clear path forward
- Instill confidence
- Delight the user
- Less thinking, more doing
- Teach users how to learn
From "UX Means Love at First Run" 
Here are some links I had bookmarked (I'm currently looking at a FTUE for one of our products. :)
 http://franklyspeakingnews.com/2012/04/ux-means-love-at-first-run/ https://blog.intercom.io/designing-first-run-experiences-to-delight-users/ http://www.smashingmagazine.com/2014/04/rethinking-mobile-tutorials-which-patterns-really-work/ http://www.kryshiggins.com/first-time-user-experiences-in-mobile-apps/ http://www.hcde.washington.edu/files/moya_ppt_creating_great_first_impressions.pdf
Relevant SE link: Are there any resources/guidelines on First Time User Experience?