People have feedback when they have something to say, not when you send them an email.
In other words: I have feedback about an app when I use the app and discover something that bothers me or could be improved. This could be in the first hour of use or it could be a month after I downloaded the app.
Why the delay? I don’t always run the app immediately. I don’t always start using the app heavily immediately. I don’t use all available functionality (especially the more advanced options) immediately. Even if something bothers me it might take 20 occurrences to bother me enough to leave feedback. Etc…
Instead of sending an email, make it easy for people to give you feedback about the app when they have something to say.
I would do it by adding a feedback button in a visible place, like in a main window of the UI.
That button would launch a browser with a webpage like https://blog.kowalczyk.info/contactme.html where people can type their feedback, press a button and that will send an e-mail.