The time required is only 8 days. The time allocated was 10, which would be on a higher estimation. The major activity is only the fixing the roof components to the wall frames and placing the skylights. The necessary designs for the skylights could be prepared and fabricated early. Placing this could be undertaken along with the roof work. And the attaching the TV antenna shall also be undertaken along with this.
Plumbing and wiring: The plumbing and wiring could be simultaneously undertaken and requires 4 days each for this activity. As the it involves only fixing up of he components 6 days of plumbing could be reduced to 4 days as equivalent that of wiring.
Plastering: plastering work need to be undertaken after the plumbing and wiring, as any damages to the structure could be rectified at this stage. 4 days would be enough for this operation as it involves only covering the walls with appropriate mortar.
Foundation:, Frames: 14 December 2008, Roof: 22 December 2008, Skylight: 25 December 2008, TV antenna - 28 December 2008, Plumbing and wiring: 30 December 2008; Plastering: 3 January 2009; Finishing: 7 January 2009, Painting: 7 January 2009; Carpets, curtains and sides: 13 January 2009 and landscape: 15 January 2009.
The critical activities that would effect the shorted time required to complete the project are foundation, frames, roof, ...