如何从今天起至少8天前选择日期选择器？

I try to make a date picker where you can only choose dates from 8 days left. If we have the date 09 / 05-2015 you can not select (8,7,6,5,4,3,2) but you can choose the 01 / 05-2015 and go down. How can i make that?I try to make a date picker where you can only