How late must an NI Railways train be before I can claim Delay Repay?

At least 30 minutes. Translink publishes a 30-minute threshold for eligible local NI Railways journeys.

A delay of 30 to 59 minutes attracts 50% of the relevant single journey cost; 60 to 119 minutes attracts 100%; and at least 120 minutes can attract the full return fare equivalent. The claim is assessed against Translink’s scheme conditions.