For me, it only takes a day to reach IMO Karachi from IMO Islamabad. As for customs, cleared doesn't imply that duty will not be charged. If duty is applicable postman brings a slip and you pay him when receiving the parcel. However, I don't think your parcel has gone through customs yet. Tracking status on Pakistan Post website will be more accurate than USPS once parcel is in Pakistan. If parcel goes to customs it should appear in the tracking on Pakistan Post website. In my experience, customs evaluation is done at the local IMO i.e. Islamabad IMO simply forwards the parcel to Karachi and the customs evaluation is done over here. I have never had to pay any duty on any parcel before the one that is currently stuck at customs, other than the 45 rupees handling charges which I pay to the postman.
Pakistan Post tracking for one of my recent parcels,
17/10/2017 09:38 | AMSTERDAM E INTERNATIONAL MAIL | insert item into bag in origin country |
22/10/2017 06:53 | ISLAMABAD INTERNATIONAL MAIL OFFICE | receive item at office of exchange in destination country |
22/10/2017 07:26 | ISLAMABAD INTERNATIONAL MAIL OFFICE | send item to DMO KARACHI FGN POST in destination country |
23/10/2017 06:08 | IMO Parcel Karachi | receive item at office of exchange in destination country |
26/10/2017 07:21 | IMO Parcel Karachi | Insert item into domestic bag |
Another one which is currently stuck at customs,
10/11/2017 10:36 | AMSTERDAM E INTERNATIONAL MAIL | insert item into bag in origin country |
14/11/2017 04:50 | ISLAMABAD INTERNATIONAL MAIL OFFICE | receive item at office of exchange in destination country |
14/11/2017 07:47 | ISLAMABAD INTERNATIONAL MAIL OFFICE | send item to DMO KARACHI FGN POST in destination country |
15/11/2017 05:45 | IMO Parcel Karachi | receive item at office of exchange in destination country |
16/11/2017 10:02 | IMO Parcel Karachi | send item to customs in destination country |