Resubmitting with more information:

ISP: Cox
Type of Internet Connection: Cable
Internet Connection Speed: 100 mbit/s
Date & Time: 2:15AM EST 7/4/2015
Frequency: Always
Character Name: Del Dugrega
Race: Au Ra M
World: Ultros
Class/Level: Monk/60
Area and Coordinates: The Lavender Beds (X:13, Y:9)
Party or Solo: Solo
NPC Name: N/A
Monster Name: Lv50 Striking Dummy
In-Game Time: 2:35 pm ET

Using Snap Punch or Demolish will apply Greased Lightning the moment the skill is pressed, opposed to granting the buff when damage is applied / animation completes.
Timings of buff applications from form changes and Twin Snakes vs Greased Lightning demonstrated in this gif http://i.imgur.com/6jHiP5s.gifv
It has been this way since Heavensward early access release, when prior to 3.0 greased lightning grant would be at the same time Coeurl form changes to Opo-opo form.