We plan to make the difference between the "0" space and the return space more clear in the next version of the rules.
While it looks like a complicated way of doing that, it has two main benefits. First, you always get a round of actions between whaling and returning home. Second, the math is very simple because if you are on the 4 space during the action phase, you return at the end of the current round plus 4, and have 4 whaling phases.
No complications, I just wasn't using my eyes!