This WA will show a glowing Power Infusion icon when triggered, informing you that the designated target has asked for the buff. The WA currently triggers from the received whisper command "PI me".
The trigger can be changed to wording of your preference. View the attached screenshot for how to.
When used with the following macro, this minimizes down time and allows you to get Power Infusion out at the precise time.
Simply replace " playernamehere " with the name of your designated target and you're good to go!
/cast [@playernamehere] Power Infusion