Below is a template that the President/CEO can borrow from as a guide for announcing the "why" and "when" of the survey to all employees.
I believe that you and our people are the most critical component to our success. You produce the [products and services] that we deliver to our customers every day. We need to understand what’s important to you and how you are really doing at work. Perhaps I have some blind spots. If so, knowing these will help us create an environment where you can perform your best and thrive.
This is why we’re doing an employee engagement survey on [date/time]. Here’s what’s in it for you:
It is short – it takes 6 minutes to complete
It is safe - conducted and controlled by a 3rd party (Emplify a 15Five brand) to ensure trust and 100% confidentiality – no individual results will be available to anyone here (not even me), so please be honest and candid
We will act - this is not just an exercise. We intend to share company-wide result trends as well as choose actions. We will give results access to our own leaders for their area of the business.
You will receive an email in your work account (from "firstname.lastname@example.org") and/or a text message on [date/time] inviting you to participate by clicking on the survey URL
You will have  business days to spend the 6 minutes to complete the survey