WoWDB

Tips:

•  Lovely Fireworks can be traded among players.
• The rocket is a use-and-target item, not a use-and-cast, so make certain you can easily see the ground.
• Find a secluded area with little traffic from other players.
• Disable big addons that use large amounts of memory.
• Place the item on your action bar.
• Reduce your GCD by using haste-boosting items and spells, such as Bloodlust and Potion of Speed.
• Go into the Achievements pane (default keybind to 'Y', I think) and go to World Events -> Love is in the Air, check the box in the bottom left corner of "The Rocket's Pink Glare". It will display the 20 second timer once you start shooting off rockets.