The Sunshine Progression server operates on a seasonal basis, distinct from the traditional four seasons of the year. In this context, “seasons” refer to the server's temporary nature.

• Initiation: Each season begins with a fresh server seed, typically introduced shortly after a significant Valheim content patch is released.
• Isolation: New progression servers are launched in isolation, prohibiting character transfers and allowing only new characters until the final boss is defeated. Once this milestone is achieved, the isolation restriction is lifted, permitting the free transfer of existing characters. Please note: Server isolation does not affect your character data and is server-wide. Individual characters are still required to complete the game and acquire final boss kill flag on their character progression file to gain access to other servers.
• Duration: Seasons generally last a few months, extending until the next substantial Valheim update. However, the duration can be adjusted based on player demand or to refresh the gameplay experience.
• Announcement: When a new progression season is announced, the current progression server is given a closing date. This date is usually set around the time of the Bonemass boss event in the new progression season. Specific dates are provided in the #announcements channel on Discord.
• Closure: After the closing date, the old progression server will be permanently shut down.

We give players ample time to transfer their resources to the Main server before the old progression server closes. If you haven't yet unlocked access to the Main server, we encourage you to seek assistance on the Sunshine Discord. Our seasoned Vikings are always willing to help with boss challenges and resource transfers.

For the latest information and updates concerning the commencement of the new season, keep an eye on the #announcements channel on Discord.

A typical timeline for a new Prog is about 6-8 weeks after a large release hits Public Test.
When a release hits PTB there are several weeks where bugs are found, changes are made by Irongate and modders try to fix their mods.
Then there is the actual release - which inevitably breaks mods again. Once those are fixed - typically several more weeks - a new Prog is released following the steps above.

If you are already on Main you do not have to work through a new progression server.
If you choose to “sit out” a prog server you will not have access to it until after the last boss is released.
After that you may access it with any character that has already gained access to the Main server
That said, most players enjoy encountering new content in the context it was designed for e.g. Fighting bears for the first time in Deer armour with stone age weapons is a bit more challenging and fun than just rocking up in enchanted gear and one shotting it.