[rules-users] Execute only on most current instance

I have a rule that I only want to execute on the most current instance, where init_dt is closest to today. Anyone know of a way to do this? For instance, I have a few objects with init_dt of Jan-12-2005, Feb-06-2005 and April-01-2005. I only want to execute the rule on the instance which has an init_dt of April-01-2005. Every object will have a valid init_dt in the past (before today). Thanks in advance, Brian Enderle