Zekkyou on 01 January 2014
I'd recommend just going right into the 2005 series. While it is a sequel to the original, it was made 20 years later so it was written to be watchable with no knowledge of the 60's to 80's series. The first few episodes of the 2005 series are rather slow, and a tad dated by now, but things really pick up by episode 6.
If you are in a rush to catch up it's possible to start with series 5 (2010), but Season 8 isn't planned to start until some time in the second half of this year, so you have plenty of time :)
*runs off to watch The Day of the Doctor again*
