Well he was given 10 life sentences, so perhaps after serving 3 would be an appropriate time.
Its certainly no laughing matter, but you have to see the irony in a bloke who wants to seek release to spend time with his Son, he wasn't thinking about a Fathers time with their Son when he was squeezing the life out of their Sons.
Would be staggered if the courts even pondered the thought of imposing a parole date for Wagner, let alone actually going ahead with it. One of the few characters where literally locking him up and throwing away the key is most appropriate.
British podcast Redhanded Snowtown Ep. 55 has picked this up. In the intro they explain their research so there's no complaints, it's quite good. Some in there I had no idea about, like one of their first victims lay in the morgue unidentified for a year. Also explains the background in some detail, how the group evolved and Wagner's relationship history which was quite interesting.