As @Aaron Hockley30 mentioned, there's a whole number of ways you can think about this.
What I suggest to clients is to think about the end first. What is the goal? What does that look like? Then work backwards.
If you have a monetary goal or an enrollment goal, then work backwards to think about how big of an email list (or how many people you need to see the offer) you need in order to get to that goal.
Another strategy that's worked for clients, especially if it's the first launch of a course is to pre-sell it. So that even now, on June 2, you open up enrollment (usually with bonuses or discounts) and get people to buy before it's launched. Then you'll not only validate that people will pay for it, you'll get testimonials and feedback prior to the official launch date.
This will drive interest during your official launch because potential students will see themselves in existing students' results.
The pre-sell also helps narrow down your pricing. You'll get to see what people are willing to pay you for the course before it's fully complete.