Can I start the automation from a Past date

Yes!

Go to the automations page in the settings menu. Click to the "Review" tab, and look for the automation date listed below the calendar.

If needed, you can click "Deactivate", then choose a new automation date.

The next time the automation runs, it will process all days since that date. It is fine to choose a date in the past. The integration runs once per day in the morning, so if you adjust in the afternoon, you may not see the journal entries appear until the next day.