Let's do the 80/20 rule exercise.  20% of the 195 centers have 80% of the 2400 patients on average (i.e. top 20% have 4% of total patients each).    

That lands up with 49 patients each for the top 20%.  So even if you got at the rate of 2/day, you can finish off the 80% of the patients in 25 business days.  

The remaining 80% of the centers have about 3 patients each...so if we start those follow ups AFTER the top 20% are finished, we get another 2 days.  In total, 27 business days.  So 1 month and 1 week in calendar terms, in this scenario.  

Since we started on April 18, that means we are already down with the follow up as 27 business days would mean May 26.

Assuming 2 weeks for data entry/final checks etc., that suggests June mid for data lock.  Add 3 weeks for data tabulation, we land up with...June 30!

Holy cow...they were not joking re "Mid calendar year"...this means July is the big month.  GLTA!