The Julfest plates were issued every year, but there are unknown years that have not been seen. 1937 as shown here is the earliest that I am aware of. They really start to show in 1940,41,42,43, and 1944.

The Julfest references pre-Christian pagan ritual. The SS under Heinrich Himmler sought to fall back to these times in which many of the Christian rituals had evolved dating back to 321 A.D and the rule of Constantine. Pagan ritual was banned in 341 A.D, And  pagan worship was forbidden in 353 A.D. In 356 A.D The worship of any non-Christian images became a capitol crime.

Although the SS had taken on many pagan rituals during the course of the 3rd Reich, Christianity thrived and pieces geared towards the public had Christian connotations and there is much evidence that Christianity was utilized and even upheld by the SS at the same time.

This is evidenced by the commercial Julfest plates as well.