The new President will be able to start the ball rolling very quickly, but many expected or hoped-for changes cannot be immediate. The changes may easily take a year or more.
Please forgive a little 'inside baseball' on how Federal regulations work. There has been a huge level confusion in the press over how the Obama Administration has taken actions without getting laws passed by Congress. Executive Action and Executive Orders are not the same thing, although an Executive Order is one form of Executive Action. Publishing Federal Regulations is another.
An Executive Order (EO) is a very specific formal document signed by the President, giving orders to the Executive Branch to take specific actions, including publishing regulations in the Code of Federal Regulations (CFR). An Executive Order does not apply to the general public, nor to the Congress or U.S. Courts, as a law does. It applies only to the Executive Branch departments or agencies named in the Order. You can find all EOs back to Herbert Hoover at the National Archives at
https://www.archives.gov/federal-register/executive-orders/disposition.html
The legal theory is that every EO must be based upon authority granted to the President in some Public Law.
Most of what the Obama Administration has done without Congress, including changing the rules on fingerprints for arsenal trust members, has not been through EOs, but through Department or Agency Regulations, published in the Code of Federal Regulations (CFR,
http://www.ecfr.gov), after a publication process in the Federal Register (
https://www.federalregister.gov/) and a public comment and review period, all required by law. Federal Regulations, just like EOs, are supposed to be based on authorities in law, either directly, or as directed in an EO, which is itself based on a law.
So, the new President will be able to immediately order departments and agencies to change many current regulations. However, the process to change those regulations must go through the publication, review, and public comment period required in law. That process will take many months, especially if the responsible department or agency slow-rolls first preparing the initial draft, and then reviewing and dealing with the public comments.
This entire slow regulation process is, by the way, why the current administration has been rushing thousands of pages of new regulations out in final form since the election.