For most ByeRoaming data plans, validity starts when the eSIM first connects to a local network in the destination — not when you purchase or install. You can buy and install over Wi‑Fi before your trip; the countdown (7, 15, 30 days, etc.) usually begins after you land and attach to a partner network.
What to do
- Install before you fly (Wi‑Fi required for download).
- Keep the travel line ready but idle until you arrive (unless a specific plan says otherwise at purchase).
- On arrival, enable the travel eSIM for cellular data.
- Check the plan card in the ByeRoaming App for the exact duration and any exceptions.
When data runs out, see What happens when my eSIM data runs out?. Destination example: Japan eSIM.