Possible Clues:

• Everybody ready, like moulded jelly
• 'I'm ready'
• "Ready?"
• The concrete is wholly hardened already, by the sound of it
• Everything ready to go - like cool jelly?
• Informally ready, as jelly may be
• Ready to begin, like hardened jelly?
• ''Ready when you are!''
• 'Ready when you are!'
• 'Everything's cool'