[quote=@Bishop]
Hello!
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Let's say that ideally, everyone posts once a week. After how many weeks would we be able to jump to the second part?
[/quote]

I'd say it depends a lot on both the characters and the players. There might be someone (or several someones) that decided to check out all of those weird things almost immediately, 

There won't ever [i]not[/i] be these mythical/magical/whatever-you-wanna-call-it elements to the island, but I suppose that to most shipwrecked people, they won't be as interested in finding out what that odd altar at the shore is and means as they would be in finding food, drinkable water and shelter.