Hell, a year or more.
Depends on how impatient you are. Yes, that statement is serious.
The longer you leave the beer in the bulk-aging vessel - 'secondary' isn't really an accurate descriptor - the more yeast will settle out. Nevertheless, unless the strain is quite flocculent there will still be cells in suspension even after six months, a year. Depending on the strain, it may not be a lot
of cells, but they're in there, never fear.
Now, the fewer cells in the aged beer, the longer bottle-conditioning will take to accomplish. If there's three cells in the 12-oz bottle, it'll take much longer for them to multiply a bit and carbonate the bottle. That's what I meant about patience - the longer the beer is in the aging tank, the more patient you'll have to be about bottle-conditioning.
If you do
decide to re-seed the batch before bottling, there's no need to use the same yeast as performed the main ferment; you can use a very neutral strain, like S-05 or Nottingham.