Having been involved in travel from 1968-2015 it always brings a smile to my face when I see questions like this.
Summer scheduled use to be released around November of the previous year and Winter in April. Tour operators did not put their Summer holidays on sale until New Year's Day (That was a manic day and of course computers didn't exist).
Now we all want to see timetables year in advance - and even before Slot Controlled airports have had their initial applications approved (Yes I appreciate that some slots will be automatically allocated on a grandfather rights basis).
Sorry about that!!