The immigration reform by President Obama has several different provisions states Brian D. Lerner. Many of those provisions have different dates upon which they will become effective.
The immigration reform provides a new DAPA, an expanded DACA, updated Prosecutorial Discretion standards through different priorities, expanded standards for eligibility for the Provisional Waiver and various other matters.
Brian D. Lerner, Immigration Attorney states that there are different priorities and exceptions to the those priority standards.
The revised guidance shall be effective on January 5, 2015 states Brian D. Lerner.
The revised guidance in the effective immigration reform memorandum applies only to foreign nationals encountered or apprehended on or after the effective date, and aliens detained, in removal proceedings, or subject to removal orders who have not been removed from the United States as of the effective date.

The actual Memorandum put out by Jeh Johnson
Brian Lerner states that the official memorandum
“Civil Immigration Enforcement:
Priorities for the Apprehension, Detention, and Removal Of Aliens,” (ICE, John Morton, Mar. 2, 2011), “Exercising Prosecutorial Discretion Consistent with the Civil Enforcement Priorities of the Agency for the Apprehension, Detention, and Removal of Aliens,” (ICE, John Morton, June 17, 2011), “Case-by-Case Review of Incoming and Certain Pending Cases,” (ICE, Peter Vincent, Nov. 17, 2011) , “Civil Immigration Enforcement: Guidance on the Use of Detainers in the Federal, State, Local, and Tribal Criminal Justice Systems,” (ICE, Dec. 21, 2012) , “National Fugitive Operations Program: Priorities, Goals, and Expectations,” (ICE, Dec. 8, 2009) , “Policies for the Apprehension, Detention, and Removal of Undocumented Immigrants,” (Nov. 20, 2011).

Watch Brian D. Lerner speak about immigration reform enforcement priorities