The client has delayed the installation of the contract by 7 months. On a project that was let and priced 2 years ago. this is the first formal notification even though an early warning was submitted in Dec 2016 forecasting additional costs.
The issue to be mindful of is whether you are not time barred from notifying any of the matters, under clause 61.3. The NEC contract is based upon the principle that matters are dealt with as you go along rather than left to be ‘wrapped up’ at the end of a project.
Notwithstanding the above, however, it sounds like there are actually several issues which have caused delay, which are required to be administered separately, especially if they have occurred at different times and are for different CE reasons…
From a practical point, notification of any compensation event should explain the matter in sufficient detail to allow the Project Manager to decide whether it is a CE. Ideally, refer to the clause you are notifying under and try to align the description with the wording in the clause. Often a simple timeline of events is a useful tool to explain things.
Hopefully you will have regular meetings which should provide a suitable forum for discussing such issues anyway, so you can talk to the PM and explain things in further detail if necessary, following a formal notification.
Note that any event, except for event attributable to the Contractor, that affects the Completion Date and/or Key Dates is a Compensation Event (CE). Explain such in your notification.
Then you must submit an updated Programme showing an adjusted planned Completion, Completion Date, and Key Dates due to the delay together with the corresponding resource loading.
Further note that, Sub-Clause 63.1 does not apply on CE due to changes in Key Date and/or Completion ( 60.1(3) ) hence, it is not time-barred.
The answer to your specific question is enough evidence to prove your entitlement to the Project Manager. This will be both in terms of the detail of the cost, but also impact upon the programme.
However – the better answer to your question would have been to prove this as you have gone during the seven month period. Typically on a project you are required to submit a revised programme every four weeks or every month. On that programme it is a requirement to show a planned Completion and Completion Date milestone. Any period that your planned was moving beyond the Completion Date then you should have notified a compensation event (not an early warning) at that time assuming it was one to justify that that event had caused the issue.
The idea with NEC is to justify time delay as you go not in a big chunk at the end. An early warning is notified when there is an issue that COULD affect in simple terms time, cost or quality. As soon as this IS an issue that IS affecting time, cost or quality then it should have been notified as a compensation event and a quotation submitted. If it is difficult to forecast at that point then Project Manager assumptions can be used to caviat what the quote should be based upon.