I'll go by the month's and give pro's and con's:
+It would be a side-by-side release with Japan.
+It would rock.
-Highly unlikely Nintendo would release it in America so soon.
-Mysterious Dungeon comes out.
+Game's for the DS have come out in a months time from their JP date.
-Interferes with Ranger, which is supposed to lead up into D/P.
+Nintendo could do a two month translation, if they wanted too.
-Probably will focus on the Wii, as it supposedly comes out.
+Could get alot of money from kids buying it for Christmas.
-They have never released a Pokemon game in December.
+Many kids have money left over from Christmas.
+About 5 months since Japan release, R/S was about the same amount.
+A great time, half a year after Japan, kids still have money maybe left over.
+My birthday. XD
So, I'm going for a January or February release. What does everyone else think?