How I got my first 10 beta testers without an audience and how can you do the same?

Hey, I just launched Hippotweet.com and after 1 day, I already had my first 10 beta testers, without any audience !
There is 3 method that I used

1. Cold email
   I've contacted 10 really very targeted people through personalized cold emailing. I used Lemlist and LinkedIn (for targeting people) ! 2 peoples respond positively and became beta users ! These people are founders/growth hackers that already use DM automation tools but for Linkedin. I just proposed to try the same but for Twitter.

2. Cold Twitter DMs
   The 6 others came from a Hippotweet's campaign (my own tool). I targeted people who liked a Tweet from a SaaS influencer about finding SaaS users.
   I contacted 82 people and I (currently) have a 23% response rate. On this 23%, I converted 6 people to beta users.
   My messages sequence was very simple and honestly, not so good.
   Only one message:
   "Hey, I'm searching for beta users for my SaaS, it will help you to find new customers for your business through automated Twitter messages for free (except some feedback). Are you interested ?"

3. Tweet response
   Two users came from a Tweet response where I talked about Twitter DMs (https://twitter.com/pvanhecke_/status/1492166169473830920), they asked me if I used a tool for contact people through cold DMs. I respond that I use my own tool: Hippotweet
   Both became beta users

If you want to follow my journey, do not hesitate to follow me on Twitter (https://twitter.com/pvanhecke_)