if[Not]LastUsed>XXs=action
The ifLastUsed timer will perform the action immediately at the start of combat or if you changed targets. It will then wait XX seconds before performing the action again.
Also see ifTimer, everyXXs.
Legend
<item> is a placeholder and the entire string including <> should be replaced with the appropriate value. [text] means text is optional. {option1,option2,option3} means one of option1, option2 or option3 must be chosen. Batteries not included. UnitId can be any valid UnitId sequence as described in http://www.wowwiki.com/UnitId. Capitalization of UnitIds is not important. e.g. player, pet, target, targettarget. If the UnitId is optional, player is assumed.