Here is how the holiday decorating begins in The Amazing Valentine's Day.
At the Golden Oak Library, Yuna and her friends started decorating the supplies for the party.
Princess Yuna: Let's see now.
Somnambula: I trust you're looking forward to this occasion, Princess Yuna?
Princess Yuna: Yes, It's going to be the best party ever.
Somnambula: Yes, A most heartwarming emotion the anyone or anypony would treasure until the very end.
Dipper Pines: You sure spoke some riddles, Somnambula.
Somnambula: I know, Dipper.
As for Rockhoof, He brought out a special mighty helm heart shape rock.
Rockhoof: What'd ya think of this, Sugar Apple?
Sugar Apple: Very nice.
Star Swirl the Bearded: Twila, Would you like to help me and Mistmane with some snacks and drinks?
Princess Twila: Would I!?
Stygian: Yes.
So, Twila and Stygian help Star Swirl and Mistmane with some snacks and drinks.
Thunder Spectrum: Flash, Is this scenery high enough?
Flash Magnus: That's perfect, Thunder.
Somnambula: Very good.
When the sign was put up, It says "Happy Valentine's Day and Hearts and Hooves Day".