Curtailment and load-shift programmes open on the network right now.
You name the meters after the utility accepts your capacity
offer — at confirm, not init.
Revising before the event costs nothing. The same shortfall found afterwards is charged back at the penalty rate — so if a site drops out, say so now. A multi-block commitment revises block by block: only the ones that changed need a new number.
Ask the utility what it has measured against this contract.