You will be notified via SMS at the following instances:

1. At point of gigaRoam pack activation
2. When there is 0.5GB left in your gigaRoam pack
3. When there is 6 hours left to expiry of your gigaRoam pack
4. At the point of expiry of your gigaRoam pack

You can also view the validity end time of your active gigaRoam pack from your dashboard. It is displayed under the roaming balance bar in the format "Valid till DD MM, 00:00Hrs in SGT".