To start a delivery time optimized mailing immediately, you'll want to create a "Contact based" and "Blank workflow"..

Underneath the "Contact enrollment trigger" step you'll add an "Email delivery time optimization" step and select the "Delivery window" which is the time period that you are providing to Seventh Sense to personalize the delivery time of your mailing.

For email deliveries that you want to start immediately DO NOT use a "Contact enrollment trigger".  Leave this blank as you will manually enroll your lists into the workflow.  If you use a starting criteria such as "Member of a list" and that list is active, people that meet that starting criteria AFTER you want to send your mailing will be enrolled in this workflow.  For example, if this is a newsletter mailing, you don't want new contacts to get that newsletter sent to them 3 weeks after the newsletter was sent.

You'll then add a "Send email" action and select the email you want delivered.

"Review and publish" and "Turn on" your workflow.

Manually enroll the list(s) of contacts that you want included in the mailing into the workflow.

Click "Monthly Subscribers - Seventh Sense Blog"

Your completed workflow used for delivery will look exactly as below. You can also track the progress of contacts moving through the workflow at each step by clicking on the action and then look at the "Contacts in action" tab or by looking at the "Details" page in the workflow.  You can also track the performance of the email in the email section of HubSpot like you would with any other mailing.

Contact enrollment trigger
No triggers set. Contacts can still be enrolled manually.
1.Email delivery time optimization
Actions
Add a "Send email" workflow action step below which will deliver the email to each contact at their optimal time within the selected delivery window.
2.Send email
Actions
Tutorial Email - 1

Once a mailing has completed, you can delete the workflow entirely. All of your performance data and reporting will still reside in the email section of HubSpot. The workflow is simply used as the delivery mechanism when using HubSpot.

Immediately start a delivery time optimized mailing in HubSpot