This is a very important question, because without a clear road map and set of priorities, such a president runs the risk of having his pro-freedom agenda stymied by the various vested interests that benefit from big government.
Of course, just as the welfare-warfare state was not constructed in 100 days, it could not be dismantled in the first 100 days of any presidency. While our goal is to reduce the size of the state as quickly as possible, we should always make sure our immediate proposals minimize social disruption and human suffering.
Source (indirectly):
http://www.yaliberty.org/yar