You have 180 days by default to install and activate the eSIM. If your plan has a different window, it is listed as Validity in the plan's Technical Specs; the exact deadline is the Activate Before date in your order email.

When you scan the QR code before your flight, your phone only downloads the eSIM profile — the line you then name (e.g. eSimExpress Travel). On arrival-activated plans this does not start the validity period — but if the plan is set to activate on scan, or your current network is already covered, it can start at installation.

On arrival-activated plans, turn off Airplane Mode and let the eSIM connect to a covered network — the validity period starts on that first connection. If the plan is set to activate on scan, the countdown already started when you installed it (and a regional or global plan whose coverage includes where you are can start without waiting for your destination). Switching the line off afterwards does not pause the countdown either way.