You can activate it anytime, it’s instant. In fact I accidentally activated my giga Sim even before receiving it by logging in and clicking on activate in the app.
Received the sim card on 5 Jun. Going to activate on 30 Jun. Brother going to use up his prepaid sim balance before switch over.
Someone here said can wait 1 month to activate before become invalid.
Sent from Mercedes-Benz E250 using GAGT