Please be warned
Please be warned, so you do not make the same mistake. Although it looks on their Homepage like you can buy the esim in advance, they are activated the day you buy them! So buy them on the first day you want to use them, despite what they are telling you. I bought esim codes from other providers and they start their time period from first use. I can't say anything about the functionality as I do not buy from them ever again and it took the support quite some time to discover this "problem".