to keep the beginning date in the present, the option would be to write code that gave you a < 90 day window, or keep moving your end date farther into the future with every change of data that moved the start date of the estimator, just to keep the 90 day period.
since it is a 90 day estimator, you may find yourself in the middle of that period of time. that sorta makes sense if it is looked at as a 90 day window.
I have a 70-odd year life expectancy, which has a start date some time in the past and an end date some time in the future. I find myself almost constantly in the middle somewhere.
I'll admit I misread the intent of the estimator when it was announced. I thought it was going to be, "for those of you whose cars will be arriving within 90 days, this will tell you when to expect delivery". In other words it would come up empty until you were 90 days away from taking delivery and then it would track the progress for the last 90 days. that would have been nice, and useful. For those who needed to make plans, very useful.
Either that was not the intent or someone got the programming wrong.