Yes. This would be accomplished by inputting the desired future date into the By Custom Date field for the 'Days as Member' Calculation method. The 'Days as Member' Calculation method is found in the Access Rights tab of an individual's Member Details area. When the custom date is set to one in the future, MemberMouse will display the 'Days as Member' as a negative number, and this will decrease until it reaches the future date you have chosen. That future date will be Day 0 - the first day of membership.
The 'Days as Member' Calculation method determines how MemberMouse will calculate the number of days someone has been a member. This is used primarily in determining where a member is in a drip content schedule and therefore what content they get access to. By default, the calculation is done based on a member's registration date, but you can choose to have the calculation done based on a custom date.