As answered in the FAQ on the official NAFEZA website, the exporter should submit ACI filing when he has all the documents ready (when they are issued). There is no hard deadline or penalty for late filing.
The idea is that exporter files ACI as soon as the finalized documents are available, to capitalize on the faster digital process.
If you send ACI only one day before the cargo arrives, your importer will not get the benefits of the new system (green line and immediate cargo release).
With the newly introduced delegations feature on the CargoX Platform, the exporter company can now invite another registered and validated company (freight forwarders, agents, and similar specialists) to become its representative for ACI filings to the Egyptian Customs Authority.