Although the buyer pays for the freight and chooses the freight forwarder or carrier, it is still the practice of the seller to contact the carrier and book the shipment. Only they know when the goods are truly packaged, labelled and available at their loading dock and the documentation is complete and ready. Sometimes an appointment for pick up has to be made and there has to be a two way conversation between the shipper and the carrier to make arrangements for transfer of documents and goods.
The shipper should also send a message to the buyer to confirm the transport details, etd, eta, vsl, hbl etc. Doing anything less than this only makes the seller/shipper look sloppy and unprofessional.