A week, that's generous. You can burn 2gb plan up watching a 2hr movie on Netflix . I've ran up 2x my normal monthly usage already this month w/ YT now streaming in 720p, alone. I've got another week on my billing cycle. I'll be over 20+gb before then. That tiered plans crap is such a blatant scam on consumers it's unbelievable they can get away with it. No wonder all they want to carry are 4g phones.
it depends on the month, some months i watch movies a lot on my phone and hit around 25-30gb. att throttles at 3gb and 5gb for 3g and 4glte phones, respectively. so i guess 5-6 days for lte on att, but i rounded to a week.
Note that Apple according to their website considers HSPA+ to be 3G technology, and even though AT&T considers HSPA+ to be 4G technology, they will still throttle it to 3gb same as all other 3g devices.