Counting from year 0...2025 with 366 days per year, I'm to lazy to properly account leap years, it's 741,150 possible dates (including incorrect February 29th in non-leap years) in one particular style of formatting THE DATE.
With the right tools it's a piece of cake for those who know how to do it, to try every possible date with some common formatting. Who cares if you need a few hours for one style of formatting to exhaust every possible date? OP could try them all, if he wanted.
He could even first cut corners and try first only every possible date in the intervall 1900...2025 for all date formatting styles he can come up with. That's just 45,750 dates per style. That's what I would do first.
I'm sure some knowledgable members here would and could give OP enough advise how to automate an exhaustive search.
I'm pretty confident I could do it. Might need me some read-up as it's a long time ago I last did a wallet cracking recovery (someone in another forum forgot his spending PIN for the Schildbach Bitcoin wallet for Android, didn't even remember the length of the PIN correctly, so I worked my way up from 4-digit and higher; it took me some days to finally find the correct PIN as I didn't want to use heavy energy-demanding gear for the task. I wasn't too sure if the crack attempt would finally yield a positive hit).