The best time to quit is now, and the best way to quit is 'just do it'. I started low carb and quit smoking at the same time almost 2 years ago. Because I started both at the same time I lost weight, although I'm sure it was much more slowly than it would have been if I had not quit.

Just think -- all of the time you would have spent smoking can go toward exercise to prevent the weight gain, plus you'll have a lot more energy and breath to do the exercise!

Good luck -- keep us posted about how you're doing.