Proposition 57 passed in California on November 8, 2016, but the release of eligible inmates did not happen the day after the election. That is not how ballot measures work in practice.
When a proposition passes, the implementing regulations have to be written, reviewed, and adopted before the system can act on them. For Prop 57, that process played out over months as the California Department of Corrections and Rehabilitation developed the specific rules governing who qualified, how the parole board would conduct reviews, and how good behavior and programming credits would be calculated and applied.
The measure created parole eligibility for nonviolent felons who had served their full primary sentence and cleared a public safety screening. About 7,000 inmates were considered immediately eligible once the rules were in place, but eligible does not mean automatically released. Each case still required individual review by the parole board.
On the credits side, Prop 57 also allowed inmates to earn reductions in their time served through good behavior and participation in education and rehabilitation programs. Those credits accumulate over time and affect release dates on a case by case basis rather than producing a single blanket release date for everyone.
If you had someone inside when Prop 57 passed, the right move was to have their attorney or the facility's case manager run a specific calculation based on their conviction, sentence, and conduct record to determine how and when it affected their individual release date.