I have a theory here. Just some logical speculations based on the current data available.
As of April 28 we can see that there are around 2003 applicants between 411-420 and some 453 between 421-430.
By May 04 I guess the 411-420 range has some 3000 applicants and assuming there are 200 applicants between 421-422 range.
Now since last draw was at 423, I suppose this must have taken out everybody out of the pool except < 423 applicants.
So basically we have some 3200 candidates from 411 to 422 in the EE pool by May 4.
Now lets say since then, 2000+ more applicants joined the 411 to 422 range and >2.2k joined the 423-1200 range..with PNP and job offers and what not. Considering in Apr 28 we had almost same count in this range.
So basically we have around 5500 candidates in the 411-422 range & 2.2k in the 423+ range.
Assuming CIC will invite more than 2.5k candidates on May 17, I am hoping the cut off will drop and will reach around 417-418 not below that.
If they call around 2.5k candidates, then chances are the cut off will be 420-421.
If they call less than 2k candidates, then cut off is definitely going to increase and will be in the 427+ range.
Now it all boils down to how much quota they have actually left (adding the rejection in the already sent ITA) and how they want to ration it.
If someone can confirm how many months are left for 2017, that would be great.
We can predict the ITA count in a much finer way and can predict the cut off of the coming draws.