You need to count everything you eat into the 20 net carbs.
All your veggies, any cheese or cream or eggs you eat.
During induction most of your carbs should come from veggies, keep that in mind.
It helped me a lot to use fitday, you enter all your food there and it counts your carbs for you.
I mostly used cheese and cream to fill up my carb count (and of course I enjoyed it

).
So if I had eaten 15 carbs of veggies and eggs or so, I'd use the rest for a "legal dessert".
I hope this helps answer your questions.
Good luck with Atkins