Generally, the Green Card is permanent and valid for a lifetime. It must be renewed, however, after 10 years, but this is only a formality. If you are a DV-2020 winner, then you have until the end of DV-2020 at the latest to travel to the USA and activate your Green Card. On your first trip to the USA, you are not required to stay for a long time. Theoretically, you can enter the USA and stay for only a day.
This card though is not meant to be stored away until you need it: You should be prepared to spend more time in the USA a few years after receiving the Green Card. Until you are ready to completely move to the USA, you must travel to your favorite place in the USA every year (at least once every 364 days). If applied for, you may even spend 2 years outside of the USA without losing your status. After 3 years at the latest, you should decide on if you want to permanently move to the USA. Naturally, we are only too glad to give you comprehensive support on this topic and the legalities of having this immigration visa. We are even here for you – free of charge – long after you receive your Green Card!