Hello @CraigH20464. At this time, we are not able to change the default scheduling option in your editor. However, I did want to mention that our newest editor does automatically default to Schedule For Later, which is exactly the option that you were looking for. If you were to create a new email, you would be using our newest third-generation editor and you would see this default option available when scheduling your email. Creating an email using our third-generation editor is an easy and great experience and every email created in this editor is mobile responsive as well!
Please let us know if you would like any additional information!