How long is the processing time for deferred action work permit?

It is being reported that since former president Ronald Reagan granted amnesty to more than three million illegal immigrants in 1986, the Deferred Action for Child Arrivals (DACA) is the largest program that USCIS, DHS, and other government agencies will handle.  It is indeed true that the $465 fee that you will pay will fund the new resources being created, but still expect long delays.

Like any other approvals by the USCIS, there are no guaranteed processing times.  In this case, since the total number of potential applications could easily top a million and a vast majority of them will be filed early on, expect that it will take months even for biometric appointments.

The key, therefore, is to have your paperwork in perfect condition so that it does not become a delaying factor.  Other than that the only other problem is the security clearance that has two components: the fingerprinting results are available almost instantly to the authorities, but the background search can sometimes hit a bottleneck.  Typically, what happens is that they run a query with your name and other identifying information like date of birth, height, weight, race, etc. and if nothing comes up, you are given a clearance very quickly.

On the other hand, if you ever got into trouble with the law -- and even if this type of offense will not disqualify you from a work permit -- the agency will still contact the local police to get your file.  That can sometimes get bogged down because local agencies are not always staffed to handle so many requests (trouble ahead for residents of California, Florida, Texas, and New York with significant Hispanic applicants).  Another problem that often bugs some applicants is if their name is an identical match with a terrorist or criminal, or even worse, someone actively wanted by the police.

So my recommendation is to do a good job with your application by providing all the documentation that is asked for, being truthful, and not missing the biometric appointment.