When can we eat pandoro or panettone?
It is useless to go around it too much: between the Christmas and New Year celebrations, up to the Epiphany, but for some throughout January, you get to eat panettone or pandoro every day.
Partly because you keep buying it, partly because it’s advanced.
But when to eat it to avoid gaining weight while still indulging in the whim?

Pandoro or panettone for breakfast, snack or after meals?

Panettone or pandoro for breakfast is perhaps the best strategy.

About 50 grams of panettone or pandoro (the first is less caloric and has less fat, but we are talking about a difference of about 20-30 calories per 100 grams) can be safely consumed for breakfast, associating them with something protein, to increase the sense of satiety and reduce the glycemic load, helping the action of insulin.
For example Greek yogurt, skim or soy milk, an egg white omelette. If we choose this option, it is harmful to combine other baked goods, such as cereals, oat flakes or rusks. One thing or the other, in short. Bad idea to add jam, nutella or honey to panettone or pandoro, or add sugar to milk if we already consume this dessert.

Panettone for snack is the option not to be recommended for adults, better a slice for children.

In fact , panettone or pandoro contain more than 50 grams of sugar per 100 grams, almost sixty. A 50 gram slice therefore provides more than 25 grams of carbohydrates: practically as much as two and a half tablespoons of sugar or as much as 250-300 grams of fruit. Would you eat more than two and a half tablespoons of sugar or more than 300 grams of fruit as a snack?
This is to say nothing of the calories, which would be about 200.
Definitely a snack to avoid, because it is dense in calories and not very satiating. It can be a snack for children, but in this case a small slice of panettone is better than pandoro. Precisely because of the fats. 
In short, as a snack it is a bit too much for sedentary people who already tend to get fat.

Panettone or pandoro after lunch or dinner? DEPENDS! Another last resort solution is to consume panettone or pandoro at the end of the meal. This can be an acceptable choice as long as you have not already eaten carbohydrates. In short, if we are greedy, we play cunning. Ok, always a 50 gram slice after a protein-only meal, avoiding bread or other carbohydrates in accompaniment apart from just vegetables: a slice at the end of a protein dinner or protein lunch is not a problem if we have avoided any other type of carbohydrate.

Finally, pay attention to fats.

Panettone and pandoro have a decent percentage of fat. Up to 16-18 grams of fat for the panettone, and up to 22-25 grams of fat for the pandoro, every 100 grams. So a 50-gram slice contains the fat of a tablespoon of oil or a heaping tablespoon of butter or two eggs. So during the day we limit the consumption of saturated fats (which are not to be demonized, eh!) If we have to dispose of sweet leftovers of this type.
In short: using your head you can also eat panettone and pandoro in these days of celebration, or immediately after, without getting too much trouble. And with these tips, the line is safe.
Otherwise, if you really have a sweet tooth but you also need to lose weight, try the diet with pandoro or panettone.