Focus Time for Google Calendar

Use Google Calendar's Focus time feature to add Focus Sessions to your calendar.

1. From your Google Calendar click on the Create button.
2. Click on Focus time from the calendar options below the title, choose your date and time, and hit Save.
3. The event will appear on your calendar. The Assistant will automatically begin a Focus Session that lasts for the duration of the event. 

There is no need to add a hashtag to its title or description. More details on that here. 

Here it is in action: