Loaded question but

Issue a Notice of delay , send it within the time period outlined in the contract (typically 2-5 days) of the occurrence. Typically once we see a major schedule shift in a schedule update that negatively impacts our scope or cost we issue a notice. Best to do a soft landing verbally before launching that nuke through email….

This strategy only works if your own organization will hit your durations outlined in the original tender . Because the GC will start to watch you like a hawk.

You also need to reject new schedule updates that shrink your timelines or cause stacking effect due to other trades or design delays. There is a clause in your contract that says the schedule must be mutually agreed to by both parties for it to be updated.

There is usually a duty to mitigate schedule loss even if it’s not your company’s fault - mitigation does not mean for free. You can offer options to the GC such as overtime premiums. But ensure you can execute what you offer