Not that it matters much, since few programming languages will have date and IPv4 literals, but the form you propose does collide with IPv4 notation.

IPv4 addresses in numbers-and-dots notation can contain one, two or three dots.

10.11.12 would mean Nov 12, year 10. Or the IPv4 address you'd perhaps be more tempted to write as 10.11.0.12.

Perhaps we can put the pile of poo emoji to good use?