The problem you all seem to be forgetting is that the problem is no about how a collection of people behave, but how it is possible for a single individual to deduce his own eye color given these premises. Everyone has to start with the state, "I do not know my eye color, and no one else knows their eye color."
Suppose there were two people with blue eyes, and two people with brown eyes. If the guru is not present to say "Someone here has blue eyes," There is no other information available to them that permits them to logically deduce their own eye color. They can only sit, and throw wild guesses into the air.
So, we have the guru say, "Someone here has blue eyes."
"Oh", blue-1 thinks, "It must be him. He'll leave tonight." the next morning, when Blue-2 is still there, he thinks "This person with blue eyes is still here, which means that he could not logically deduce that he was the one with blue eyes, which means that there is someone else with blue eyes. It can't be either of those two, so it must be me."
There is no way for anyone to logically deduce their own eye color without the Guru's statement. It is an absolute necessity.
Further, the reason they wait 98 days to confirm what they already know, that there are 99 people with blue eyes, is because they still cannot logically deduce their own eye color until the last day passes. No one will 'skip' days because doing so does not permit one to arrive logically at your own eye color.
Suppose I have blue eyes. I can see 99 people with blue eyes, and I know for a fact that each of them can see 98 people with blue eyes. I MAY have blue eyes, therefore, everyone else MAY see 99 people with blue eyes, as I do. The only way for me to find out my eye color for a certainty is to wait those 99 days and see if everyone is there in the morning, because in this circumstance, the only way for anyone to know the color of their own eyes is to know what other people see. You cannot skip ahead, because doing so will not enable you to prove anything about yourself.