Question: how long was Namor a homeless bum?

Most comics fans are familiar with the sliding timeline used by Marvel or DC: instead of Superman being around since 1938 or so, in the current continuity, he's only been in action for ten years or so. I think it's pretty much the same for Marvel: the Fantastic Four first went into space and got their powers ten, maybe twelve years ago.

The trouble is, there are events attached to real dates, like the Justice Society or Invaders in World War II. Now, Captain America ended up frozen until the Sub-Mariner found him frozen in a block of ice and tossed him in the ocean. Namor himself had only just recovered some of his own memory (not all of it, he didn't remember his time with the Invaders...since those comics hadn't happened yet) in Fantastic Four #4. Johnny Storm, having left the FF and hanging out in a homeless shelter, stumbles across the bearded, amnesiac Namor; he shaves him and drops him in the ocean...great thinking, Johnny.

I don't have my copy of Marvel Saga #3 next to me, but it does a great job of recapping Namor's post-war encounter with Destiny--not the blind lady that hung out with Mystique, but a mentallist named Paul Destine. Using the "Helmet of Power," which I think was a disguised Serpent Crown...this is getting more and more complicated...Destiny destroyed Atlantis and wiped Namor's memory. Or at least hid it. Namor would become a bum, wandering the streets and not even knowing who he was.

(The squarebound Inner Demons is a great look at Namor's lost years, and I may have to dig it up again. I did spent a few minutes looking for it under the title "Hidden Depths," which sounds better to me.)

The question is, how long was Namor a bum? And is that time getting longer in the sliding timeline? Does that damage the character, having him spend years out of action? Or is this just ignored? Or has that slid as well: was Namor active in the Marvel Universe in the sixties, the seventies, even the eighties; before Destiny got to him? I know there was that John Byrne missing years miniseries that was a bit of an attempt at patching holes the sliding timeline was opening, but I haven't read it. Anyone?