I write this month about the importance of having an intelligent workout plan when returning to the gym after the Christmas holidays.
In my experience this plan should encompass both when to return to the gym and what to do when you get there. The festivities are a time perfectly suited to relaxation and indulgence and this should be taken into account when returning to fitness training. Come back too hard or too late and there can be consequences for the rest of the year and the progress that might (not) be made.
Planning for the return to the gym and focusing on cardio' when doing so, both to ease back into training and to burn off some additional weight, is a good way to start. As to when this happens, my advice is to start early and not to fall into the trap of putting off the exercise.