Forecasting number of future periods, but not past a certain date

DRay I can see only having the data to project a few days or weeks, while having an end date that is months away. I think a person would generally either set only a number of periods, or a number of periods and an end date / cut-off date. If the cut-off date were beyond the number of periods, then all periods are projected. If the number of periods go beyond the end date, then projection stops at the end date, or the period containing the end date. Setting a forecast to just use an end date, without a number of periods seems an unlikely or far less likely use case.