Usually about 5-6months of age your ducks will start laying. (But of course ducks are very likely to stop or slow during winter and during molts). The vitamins should come balanced from the feed you give your flock. Your females will need a Layer formula and/or crushed oyster shell on the side...
Hi Nemobiss! Welcome! Sorry it took awhile to get your question answered, sometimes posts get missed. I bet soon others will be on go tell you their opinions too, just bcz that's the way it seems to go. But in the meantime, I'll tell you what I think. Disclaimer: I can only see a small pic, so I...