The stress of deciding is probably causing more harm than eating the egg, so don't have any at all!
On the other hand chocolate contains valuable minerals like Iron and ....(must be something else), so go ahead eat it how you want - and don't feel guilty. :-D
eating the whole lot in one day is certainly better for your teeth than spreading it out over several days. I am planning to eat nothing but chocolate on Sunday after 6 1/2 weeks abstinence, and I am absolutely sure my dentist will approve!
I say eat all the chocolate on the one day and get it over with. After that you can be good again, whereas if you try to spread it out you might just be tempted to eat even more chocolate. So have one bad day and then you can be good.
I'm no expert - just someone who loves chocolate but stays away from it as much as possible. So on Sunday, I intend to eat the one egg (everyone has orders not to buy me any more) all in one go!
Don't look at being 'bad' for one day a problem if you are trying to lose weight - it is all about a healthy approach in the long-term - one 'bad' day as you put it isn't going to do any harm - don't beat yourself up, just eat the chocolate and enjoy.
As long as it's eaten in moderation, there is evidence that suggests chocolate can have some beneficial effects, so don't worry about a little nibble each day!