E-Commerce Configuration Guide : Site Configuration Settings : Item Settings : LeadTime
 
LeadTime
Key value:
Any positive integer or 0
Description:
The number of days after today that a ticket can have for its start date. Visitors/guests are not able to set a start date before the lead time has passed. LeadTime is the soonest a ticket can be bought after today, in days. If 0, the start date is today.
Example:
LeadTime = 2
LeadMax = 60
See also:
LeadMax