Is it still a Hero's journey if a hero...?

Not every element of the hero's journey must be there in order for the story to be a hero's journey.

 

When does the journey begin?

It seems like the hero's journey begins the moment you step into that otherworld. What happens between entry and the 'real journey' may be a whole other journey. Perhaps an internal journey of initiation and preparation before the external journey begins.

 

It's better to think of the Monomyth's movement to the 'otherworld' more as a metaphorical concept than a physical movement. While it certainly can be a physical place, it doesn't have to be. What matters is that the hero moves from a situation of (relative) normality to the unfamiliar. Your hero could have lived in the otherworld for a while, but precisely because he has, it becomes his normal world. The Monomythic 'otherworld' for him would be a physical/emotional/intellectual environment which he is not familiar with.

 

Why do you ask?

 

Jesus spent years with his father Joseph learning to be a carpenter. That was his Ordinary World.

 

What Gryphos said.

 

I think you'd need to look at how the character might be faced with the decision of whether to leave his current situation or step into the new situation. The Hero's Journey begins with this conundrum. Before stepping out, he may feel entirely contented where he has been for however many years—or, he may be unsettled, uncomfortable, a fish out of water. This makes no difference. The Journey happens when the Hero is faced with that decision. So even if the Hero moved to his current location sometime in the past, and the location/situation was new for him then and is still not a place that is entirely comfortable, the Journey doesn't begin until some new event or situation presents itself requiring him to make a decision of whether to stay or leave his current situation.

You could reverse the reel a bit to see how this decision may have been made in the past—but that was a different decision. So for instance, if the Hero made a decision five years ago that led to his present situation, then the present situation either was a desired "new" situation at the time and still is desired or else it has become an accepted situation—he hasn't moved on yet, even after five years, so it has become his norm, his accepted world, uncontested, whether he's happy in it or not. But something else has now come along, five years later, that contests this world, i.e., that will force him to make a new decision between this world and another "world."