My GPA got verified in less than 12 hours. I submitted late July. I'm not sure why it took so little time, but I submitted around 11 pm one night and by the time I woke up (late) the next morning I had an email that my app had been processed/GPA calculated. In general I've heard 7-10 days is typical. I think I was just a lucky fluke that mine was done so quickly.
My letters from interfolio took about a week to be verified.
DAT I don't know. If you already took it before the app cycle opened, it should be there in mid June or thereabouts. If you haven't taken it yet, I've heard it can take several weeks to process, so plan accordingly.