THANKS :) to Linda for this data below. Jan
From the 1910 census were it says Villa is 38y and married for 14y, husband Otto's age at first marriage and age on the 1930 census yields that they have been married 15y.
If you can get someone with access to the NY state census for 1915 Ilion Village to do a look-up, she can narrow down just when in 1915 they married by whether or not they are married at the time of the census.
If the 1915 censuses follow the pattern of the older state censuses I've looked at, there should be a listing of marriages that occured in the year before the census. If they married before the census, their marriage and the date might be there.
New York Herkimer German Flatts District 11
Ilion Village German Flatts Township 5 April 1930
Sheet 8 B Ancestry image 16/28
Otto, head, owns, yes-radio, 59y, married, 44y old at first marriage, can read/write, b. Sweden, parents b. Sweden, native language Swedish, immigrated 1894 (or 84 -squinchy numeral could be eighter), naturalized, speaks English, carpenter, arms factory, wage, employed, not a vet.
Villa C, wife, 58y, married, age at first marriage 24y, can read/write, b. NY, father b. ME, mother b. NY, speaks English, type setter, typewriter factory, wage, not employed
New York Herkimer Ilion District 11
German Flatts Ilion Village 18 Feb 1920
Sheet 12 A Ancestry image 23/24
Otto, head, owns, free of mortgage, 50y, married, immigrated 1898, naturalized, 1919, can read/write, b. Sweden/illegable, parents b. Sweden,/Swedish, speaks English, carpenter, too blurry
Arvilla, wife, 46y, married, can read/write, b. NY, father b. NY, mother b. NY, speaks English, no occ
Mona, mother, 89, widow, immigrated 1919, alien, can not read/write, b. Sweden/illegable, parents b. Sweden/Swedish, illegable, no occ.
Even though Villa's name is a bit mangled... I think this is your Villa.