The timestaps inside of emailed PDF Custom Reports is always GMT
All system settings are in CDT. And all custom report settings are in CDT. When viewing the custom report it shows CDT. Only after it is emailed does it show in GMT time.
Release : 10.0.5
Component : NQRPTA - REPORTERANALYZER
As on NFA 10.0.5, NFA is using the timestamp of the user called "admin" inside of e-mailed Custom Reports PDF files.
So, to change the timestamp included in the PDF files, edit the "admin" user to change its timestamp, then re-run the Custom Report.