You can purchase an eSIM as far in advance as you would like to. Follow these steps:
- Select the eSIM you want to purchase.
- Complete your purchase.
- Your eSIM will be added to your inventory. You can find them by going into "Manage your eSIMs"
- Once your eSIM has been purchased, as long as it isn't installed, you can wait to install it until you are on your trip.