Bars have slightly more cals and carbs - and we want to make sure you go into ketosis properly before adding the bars. Also only one bar a day - and have a drink with it.
Bars you can only have from week 3 onwards - after week 2.
Just as a sidenote - if you're going to celebrate, don't celebrate with food...
Or if you HAVE to, then don't don't don't make it carbs! Or you might sabotage everything