How do I change the date a Reminder is calculating *from*?

[caftan]

I would like to have the future reminders keyed from past maintenance done before I purchased the car.

Is there any way to do that?

The system is only offering me todays date as the date from which future reminders should be calculated and strangely when I input the reminders (and all the prior maintenance) most reminders are immediately showing up as overdue.(they are not)