Freaj
... How long does it take to start to pick up an accent from somewhere else? or shake your old one entirely?
Well, I never really had much of a Yorkshire accent until I went to high school (September 1995), then by Christmas '95 I'd picked it up. I guess it's dependant on how surrounded by it you are. Some people pick accents etc. up really easily whereas some never do.
Not sure how long it takes to shake an accent off completely, but friends who have done that sometimes find themselves lapsing back into their natural accent in times of stress, so it neer really goes away.