February 2013. The vita will have a disappointing holiday and by January it should be around 4.5m. By January, the max I can see the Wii U being is ~3m (due to supply constraints). If the Wii U continues to sell 1 million per month (as Pachter predicted), then it should over take the PS Vita by.....*taps calculator* 23rd February
My prediction threads:
Wii U will sell under 40m units (made on 14th September 2012)
PS Vita will sell under 20m units (made on 30th September 2012)
Wii U will sell under 7m in 2013 - I was right