A brand new 6600 crank/BB should turn smoothly but there is a fair bit of seal and grease drag in the bottom bracket so if you throw the crank it will only go about a turn or two and then stop. This is perfectly normal and to be expected. If the crank is rough then you have a problem - maybe you preloaded the non drive arm too much?
If I were you I'd just keep going. Some people will tell you to run off to the shop but if you do this all the time you will never learn.