well, I started 2 weeks before Christmas (of all times to start a diet) I spoke to my councellor and said I didnt know if to wait until Jan and she said I could either start now and lose at least half a stone before christmas or wait until after, lose half a stone after christmas and also what ever extra I put on over the christmas period - that hit home for me so I started then... havent regretted it and have been doing well.
There is no point putting it off otherwise I think you will always find a excuse not to start. If you work, I would personally start over a weekend as the first couple of days are hard and for me it was easier when I was on my own and could drink a lot of tea etc as and when!
Best of luck in whatever you decide to do x