Delivery notice by their logistics broker will provide you guys with the container number, carrier, voyage/booking number, and possibly a bill of lading number. Once you have these, go to to the below page and select your carrier line:
http://cargotracking.utopiax.org/containertracking.html
The links will take you to the appropriate carrier's website and tracking based on the container or voyage number. This is for general tracking of the shipment, no documents or private customs info is available on these pages as those go directly to the consignee responsible for inbound customs clearance on US soil.
The 10-20 days estimate covers both the loading and transit. Here is an example schedule of a shipment we recently did from Long Beach to Sydney:
30/03/2012 Kota Jaya Laden T/S Discharge SYDNEY
12/03/2012 Kota Jaya Laden Loading LONG BEACH
06/03/2012 Kota Jaya Laden Truck In To Terminal LONG BEACH
05/03/2012 Kota Jaya Empty Truck Out By Shipper LONG BEACH
As you can see, the shipment emptied out of the LTL truck on March 5th and loaded into the container the next day. The vessel sailed on the 12th and reached it's destination on March 30th.
It depends on the transit line being utilized by your carrier, but I would expect a slightly longer transit time by a few days.