See this story of King Cnut ruling the waves.

The King Cnut School of Management is management by fiat. Declaring it so.

PM: "When will this transition to production?"

Me: "After the firewall and VM configuration."

PM: "So, can we say Thursday?"

Me: "You can say that, if you want, but you have no basis for that. The firewall hardware is sitting on the loading dock, and the RHEL VM's won't run Python 2.6 with the current SELinux settings. I have no basis for expecting this to be fixed in a week."

PM: "We can just pick a date, and then revise it."

Me: "Good plan. Pick a random date and complain when it's not met. While you're at it, hold the tide back for a few hours, too."