If they're mating, they're sexually mature, but unless you've been adding light, you may not get any eggs until early spring. I've never had any new ducks begin laying in the fall :(
Well, here's the webpage of the breeder who sold me my ducks. She does show a picture of a gold phase duck with a darker head. I guess there's just more variation than I realized. I hope you do have one duck at least! http://www.moosemanorfarms.com/about-welsh-harlequin-ducks.html
My gold females looked nothing like that, except for the dark bill. They had pale heads, and no auburn speckling on the breast.
Are they pure Welsh Harlequin?
We had a hard time sometimes with my two gold phase girls. Maybe silver is easier with their more distinct markings? We had to be very observant with the small variations between the two girls
Here are my gold ducks and silver drake. I don't understand why gold shouldn't be accepted since they come in that color. I don't get the arbitrary show rules, so good thing I just have ducks for their eggs, beauty, and silliness :D