Vikings Season 6

Vikings Season 6 just began on the History Channel.  Looking at the lineup, you can only begin to record/watch starting with Episode 3 - even On Demand.  This has happened to me several times with shows I watch.  Some have started as late as Episode 7.  I don't understand this.  If the Channel is in my lineup and can begin later, why can't I watch it from the beginning?  This is really irritating.  Sometimes there is a charge for the earlier episodes.  If I had been available to watch it the evening it first aired I would have been able to watch or record.  Answer!