Yes, I'm with m.kitchengirl, Muscovies have a reputation as seasonal layers, and yours have been recently moved. Nice looking setup, by the way!!!
Enjoy getting to know them before they start breeding like Muscovies, and you have piles of eggs and bunches of little peepers running around.
Check their accommodations and do what you can to provide nice nesting material and a couple of cubbies, perhaps. Now, I know some 'scovies will choose their own place no matter what you do, so bear that in mind as well.
There are so many Muscovy people here on the Duck Forum that watching their posts will be a big help.
Looking at the photo again, it looks like one of the ducks is full grown and the other six are a bit smaller. Could it be you have one mature female and the rest are younger? Maybe they're not as old as you've been told? Just a thought.
Enjoy getting to know them before they start breeding like Muscovies, and you have piles of eggs and bunches of little peepers running around.
Check their accommodations and do what you can to provide nice nesting material and a couple of cubbies, perhaps. Now, I know some 'scovies will choose their own place no matter what you do, so bear that in mind as well.

There are so many Muscovy people here on the Duck Forum that watching their posts will be a big help.
Looking at the photo again, it looks like one of the ducks is full grown and the other six are a bit smaller. Could it be you have one mature female and the rest are younger? Maybe they're not as old as you've been told? Just a thought.