Nikkei reports today that Nintendo is targeting March 2012 for the start of paid download content sales for 3DS. The first game to see paid download content will be the 3DS entry in the Fire Emblem series.
According to the Nikkei report, players will be able to use either prepaid cards or credit card to make purchases. The 3DS firmware was already updated for billing functionality earlier this month.
Third party publishers are also making preparations for paid download content to begin rolling out starting summer 2012.
Nikkei aslo reports that Nintendo is planning on including similar paid download content functionality in the Wii U, which is due for release in 2012.
Nintendo has not shared details on the 3DS version of Fire Emblem since its announcement in September. The game was announced with a Spring release time frame. Nikkei's report would seem to suggest a more specific March time frame.
It's likely that download content and Fire Emblem's release will be covered in tomorrow Nintendo Direct broadcast, where CEO Satoru Iwata himself will outline Nintendo's game plan through March 2012. For details on the broadcast, see this story.