Validity on the ETravelSim Slovenia eSIM starts when your phone first connects to the A1 network in Slovenia, not the day you buy or install it. You can purchase weeks in advance, install the QR code at home before flying, and the timer only starts on first connection. Installing at home is the safer option because you'll know before boarding the eSIM is set up correctly. Don't delete the eSIM profile after installation — reinstallation may not be possible.