Dont panic
Firstly you are lucky they gave estimate about when they will touch your files
We people just estimated there work from our senior applicants
This my opinion
what i have seen from decemeber 2016 ,how ndvo is working and many senior applicants will agree
in decmber 2016 ndvo gave ppr to mostly may 2016 applicants
in jan 2017 ndvo worked on june 2016 appl
in feb 2017 ndvo worked on july 2016 appl
in march 2017 ndvo gave DM to most august applicants
now in april 2017 ndvo is working on september applicants
in ,may 2017 will work on october applicants
they gave advance gift of mail in which they already told you in which month they are going to work on your files

so you should be happy that they told you in advance that when they have planned to touch ur files.

you people are lucky ,you got extra mail from ndvo