Advice on trying to talk to a guy I like

Kelsey • They have my heart ❤️ 2017 and 2019 Chemical❤️

So I’m interested in a guy. But he was sorta talking to a girl when I met him. But he started messaging me last week and I went to his wrestling show Saturday. He flirted with me. And apparently him and that girl aren’t a thing. But Sunday he didn’t message me back. My friends told me to not message him for a couple of days and see it he text first. Does that actually work the whole not texting first/ giving attention thing? 🤷🏽‍♀️