Waitlists what's your experience - I will not promote

We've now nailed down our waitlist process... User signs up for early access - we immediately email them to acknowledge this and ask them how they'll be using the product and when they'll be ready to start a trial.... We also confirm delivery of the email but so far 10/10 no response to the email. I've done some research and the guidance is offer an incentive in the waitlist email - what has your experience of waitlists been ? What kind of conversation rate? Any tips ?