Stop fooling around, 10 letters
On your mark follower, 6 letters
Announcement before go, 6 letters
It follows On your mark!, 6 letters
Next after on your mark, 6 letters
Phrase heard before the starter's gun, 6 letters
Prepare to win the lot (3,3), 6 letters
Shout shortly before a race, 6 letters
Take a three-point stance, perhaps, 6 letters
Words after On your mark, 6 letters