NEC ECC: Can you raise an Early Warning Notice when the event has already passed?

An early warning is raising an issue which could affect (in simple terms) time, cost or quality. The intent is then this will allow the matter to be discussed and see if anything can be done to avoid or minimise the effect of this event. Not a lot of point in notifying an early warning for something that you can do nothing about. If something has already happened or you know will happen, and it will either lead to a change to Prices or planned Completion then that could/should be notified as a compensation event rather than an early warning.

You don’t need to notify everything that could delay the programme especially if it is just a Contractors own delay - that will be reflected in the next programme, and in the future may or may not be mitigated. By notifying it as an early warning does not in any way change liability.

The whole idea of NEC contracts is creating transparency between the Parties but also trying to create/balance efficiencies.

It doesn’t say in your question who has not submitted the design submission. If it is the Client who should have submitted the design and that was a deliverable on the last Accepted Programme, then this would be a compensation event to the Contractor. If that then impacts their works the Contractor can assess the impact in terms of cost and time that the late design submission will have.

If it is the Contractor late in submitting the design, then the impact of the late design (if any) will be reflected on the next programme issued for acceptance. Any delay will be their liability. If the Project Manager is concerned at progress of any aspect of the work then there would be no harm in them notifying that as an early warning and then discussing at an early warning meeting if that is an issue and what mitigation measures the Contractor plans.