So you need to send en email at a specific time but you won't be at your computer. It is also 2016, can't some bot do this for me? Check out this video, is this what you are looking for?
Adding Boomerang to your email.
Click the big red button to install.
Compose an email.
You will now see this red Send Later button at the bottom.
Click that new red button.
Schedule your time.
I clicked the little calendar to pick a specific date and time.
Click the blue Confirm button.
The next screen may ask for permissions, make sure you allow Boomerang to access your account.