Season Origin Translation

Just wanting to make sure -- if you create a character from the PHB, then the season is Tyranny of Dragons,
If you use anything from the Elemental Evil Player's Guide then your season is Elemental Evil
And if you use anything from the Sword Coast Adventurer's Guide then your season is Rage of Demons?

Or is it all Real Life calendar based? If so could someone tell me the dates associated with the different Seasons?

I believe you can create characters based on any of the seasons. If you use the other guides after the PHB then you need to adhere to their newer restrictions to be AL compliant.

I only have the PHB so I create all of my characters as Tyranny Of Dragons origin. I also think the seasons are about 6 mos each.