I believe the yellow ones are pekins, the yellow and black striped ones could be mallards or rouens (mallards are smaller than rouens), and the other ones I can't tell. I don't think I have seen them before.
I say max of 4-5 days old (at least at the time of the photo) And it looks like you have 2 Pekins, 2 Rouens, and 2 Silver Appleyard Ducklings (or possibly muscovy mutts, but I doubt it coming from TSC) Great mix of ducks!!! Have fun!