Since the Roamless eSIM is a single, global eSIM that works in 200+ destinations, you can activate your eSIM whenever you wish. As long as you're in a country or region where Roamless has coverage, your activation will complete successfully.
We do recommend that you activate your eSIM before you travel, so that you can make sure it is installed and ready for use when you get to your destination
And you have nothing to worry about regarding expirations with the Roamless eSIM:
Your Roamless eSIM itself has no expiration, once you install it on your device, it stays active unless you delete it
You can always re-install your eSIM when you wish; there are no limits to deleting and re-installing your eSIM
Most importantly: If you have bought data plan for specific country or region, the plan's 30-day validity will start with the first KB of usage of the plan in its valid destiation. The data plan is NOT linked to when you activate your eSIM -so you can activate your eSIM with peace of mind