Sorry, there is no way you can date your lens. Not all Canon lenses have date codes, or serial numbers that can be decoded.

Canon might have some master list somewhere but I bet if you were to ask Canon, they would say it’s not possible.

In the past most "L" lenses had 6, 7, or 8 digit serial numbers and separate date codes. Starting in 2008, new designs were introduced with a 10 digit serial number which should contain a date code. Some "L" lenses like the EF 24-105mm have continued with 7 digit serial numbers and separate date codes. I suspect it may have to do with which factory the lens is made in.

"Consumer" lenses are a mixed bag. Some have date codes, and some don't. "Consumer" USM, Micro Motor, and STM AF consumer lenses NEVER have separate date codes. If they are newer lenses with 10 digit serial numbers you can decode the build date.

For some unknown reason, all "Arc Form Drive" consumer lenses always have date codes.

All these older, out of production Arc Form Drive lenses had date codes: (28-70, 35-70, 35-105, 35-135, 50 f/1.8 (original), 70-210, 100-200, 100-300, etc.)

These older designed Arc Form Drive lenses, that until recently were still in production, also continued to have date codes: (24 f/2.8, 28 f/2.8, 35 f/2, 50 f/2.5, 135 f/2.8SF, etc.)