Don't auto-complete AMAZON.DATE because it returns wrong results.
When a user says just a month for AMAZON.DATE slot the slot value is returned with next year's year.
For example - "whatever utterance in July?" returns 2019-07-01 for July.
As a skill developer how can I tell if the user just said "July" (which would much more likely be July this year, i.e. 2018-07) or if they really said "July next year"?
Also there is no distinction between dates with days and just months. If the user says "whatever in July" returns the same as "whatever on July 1st" - how can I tell if they are talking about just a Month or about a full date?
I suggest the unspecified values are returned as 00, i.e. "July" would return 0000-07-00, "next July" would be "2019-07-00", "first of July" = 0000-07-01 and "next year" = 2019-00-00.
That will remove all ambiguity from the returned values.