A week old baby is gonna sleep when they are tired. There's not much you can do about that. It's gonna take some time to get it switched around.

Let them sleep in a crib/bassinet at night and hold them during the day (they tend to wake up enough to stay tired every time you move). That way they get used to night and day by YOUR terms.

Congrats on the new one and Good Luck!

I have this same problem with most of my kids. Days and nights are just so easy to get mixed up. Sometimes it's just something that they have to do on their own. I have tried some without success, but they might work for you:

Make sure the baby is in a dark room when he is asleep: keep the house bright during the day when he should be awake.
Put some soft music on a continuously playing CD or white noise on when the baby is sleeping at night.
Try not to stimulate him when he is going to bed. Don't change his diaper during the night unless it is soiled when you feed him, and likewise change him often during the day to keep him awake.
Sometimes keeping him in a cooler environment will help too. Lots of blankets and clothes will make him sleepy. Generally you only need to add one extra layer of clothing for the baby than you have on yourself at that age.

I hope that helps you