One of the primary places Google looks for a date for any given page is in the URL. If a date is found in the URL, it is considered to be a strong indicator over most if not all other sources including within the response header.
From this answer: How to tell how old a page is?
4] Google looks for a date within the URL. It looks for the following
formats; YYYMMDDHH - YYYY - YYYYMM.
These may not be the only formats, but after a lot of research at the time the question was asked and answered, there was little to go on that was solid.
The URL is one of the strongest semantic clues for search engines just behind the title tag and before any link text. It is an important factor and part of the blended SERP result set before filter analysis is applied. A good URL/URI (domain name/path - these are really two separate entities) can really boost the opportunity to have a page found providing that it meets certain semantic standards.
As far as where along the URL to place the date, there are some criteria that need to be considered. Mostly the question is how important is the date and where along the line does it make sense to include it? If for example, you are organizing by date, then the date should come first. Of course that is a no brainer. But if you are talking about celebrity birthdays, then the organization could be celebrity/birthday/date. This would allow for other structures such as celebrity/died/date. This structure is least specific to more specific from left to right.
This answer gives a lot of information on that: Well structured URLs vs. URLs optimized for SEO