Happy New Year !
Still here and ready to move forward.
How long for Maegon and buddies to leave the spire and reach the ship ?
(at least half a day or one full day, cf first IC posts at the beginning of the game ?)
Do you expect us to board the ship then move to another planet, so that "Prologue" will end and "Chapter 1" will begin ?
Good!
You are free to move the story forward. Just make sure there is leeway for the other players to add stuff that took place during the day (your group isn't particularly quick, so a full day is needed) Maegon needs to reach the ship.
Correct. The Prologue ends when you get off Cadia! You only need to find parts, fix the ship and get moving. While avoiding the Grey Knights and any more xenos attacks. Plus any player-created shenanigans. Should be easy
Incidentally the adventure assumed you'd find a more peaceful way to get aboard the ship, leaving the daemon to cause trouble later and Xerxzes as a source of information. But I guess it just shows that no adventures survive contact with players. Even short, simple, prologue-type adventures