Well the software we use does not take into account day light savings time. With that said the first thing I have to ask is how many hours different are you from EST?
Like westcost time is 3 hours. The correct GMT for me (eastcost) currently is -4 hours. So if you lived in CA
or you where one west cost time then you would want to set it to GMT -7.
If your state observes daylight savings time (some dont) then when that change occurs then you will have to change your GMT by 1 hour to show this change.
Here is a little Time Zone table that I think works for the US states
Eastern GMT = -4
Centeral GMT = -5
Mountan GMT = -6
West GMT = -7
I hope that helps.