When shipping packages from China to the USA the packages from China can stay in customs for 5 to 7 days.
There have been times where I had a package from China remain in customs for 2 weeks but that is rare and it's likely because they had a lot of packages to get through customs before mine.
If the package has not been released from Customs after 2 weeks then you should contact the shipper to find out what is going on.
Packages that ship from China to the USA must go through customs and when they do the packages can take as long as 30 days to 45 days to reach you.
If you're not patient when waiting on packages then ordering from China is not a good thing although you can usually get products cheaper from China.
I've ordered things from China and had to wait 45 days before to get the package but it was not a hurry when I needed the package.