When is the best time to send a cold email?

Hi everyone, Im in the process of sending a bunch of cold emails to a lot of industry guys to go out for coffees. I was wondering when is the best time to send emails to different level bankers.

Essentially I want to maximize my probability of having my email read but dont want it to be at a time when they wont answer it (an email sent at 4 am obviously will be seen but quickly discarded).

Any advice or tips from experience or even advice from the guys getting the email?