The Mapping activity for a new supplier can take different time depending on the method of data transfer.
For an Integrated Supplier: These are the suppliers with their APIs already integrated with us. In such a case we can can simply run a downloader for their data to be mapped. Our speed is 500k mappings per day. The first download would take some time but the consecutive data download is incremental and can happen much faster. We highly recommended to have all suppliers as Integrated suppliers.
For Non Integrated Supplier: These are suppliers which are not integrated with us. These suppliers can be either converted to Integrated suppliers via API integration which can take a few days or we can run their mappings via FTP. But the mappings would every time take time as per the size of file instead of an incremental sync.