After a trial in district or municipal court, the sentencing hearing may occur immediately. Otherwise, depending on your custody status the hearing is normally 2 weeks to 1 month after the verdict.
They don't happen at random intervals. In District and Municipal Court cases, the sentencings are often immediately afterr the trials, but this is not always the case. Depending on the type of case, both the prosecution and the defense may need time to prepare for sentencing and it will be continued by the court to a date certain after trial if that's requested. In Superior Court, sentencing on a felony will always be set over as there is a lot of paperwork that required to be prepared prior to a sentencing. When that is will depend on the County and the judge in the case, but again, that date will be set once the verdict is in.