Well I know you cant give the medicated chick starter to waterfowl because the dosage isnt right for them because they eat so much more than chicks do. They will be overdosed and die.
If you feed a non medicated chick feed, then I suppose you could give that to them. However, if you are wanting eggs sooner, you should feed them a gamebird feed or meat bird type feed to help speed their growth. Your egg laying chicks can also eat the gamebird feed for the time being, or better would be to seperate the waterfowl from the chicks as they get messy with eating and the wet bedding increases the chances of bad things growing and breeding that might not affect your ducks and turkeys, but could prove fatal to your chicks. My ducks and geese have a seperate pen all to themselves.
They all range the yard during the day together though.