[AbZeroNow]

Originally Posted by haguruma

And on goes the happy timetabeling based on the new info we've got so far.

Spoiler for timetable based on info up to episode 6:

[*]June 13th - Kubodera arrives in school carrying a heavy bag, seemingly absent minded. In class he excuses himself for not being able to continue and draws a knife[/LIST]
to be continued

So by now we have a pretty big net of different events. The job now is to connect them and try to make a little more sense of them.
The "making one student inexistent" thing doesn't seem to be that reliable after all if Chibiki says it's a 50/50 chance of success or failure. It pretty much implies that there might as well be something different stopping or continuing the events altogether.

The Kubodera-sensei scene at the end is in July not June.