This letter was sent at the time of the shooting in Ashland Saturday. At that point the sniper had killed 9 people (now 10). Presumably he could not know at that point whether the shooting victim would survive or not.
So, at the time he made this statement, he was thinking he had killed either 9 or 10 people. That means he started phoning the tip number after either his 4th or 5th victim. At the end of his shooting spree on the morning of Oct. 3, he had killed 5 people. Since presumably he would not have made his call in the middle of the spree, this presumably means he started calling at the end of the spree that morning, Oct. 3.
At that time, the tip number did not yet exist. But there were other numbers that people were being asked to call then. I wonder if any record was kept of the numbers from which calls were being received.