What is the typical time period after which an incoming grad student is expected to start publishing?
This wil vary significantly according to advisor, but I'd say a typical plan is:


Years 1-2: coursework, begin research
Summer of year 2: Small research publications (in my field, 2-4 page conference proceedings, small steps)
Year 3: Get some real research done, more small papers
Year 4+: ~1/2 paper a year, ish


However, the variance may be too great for this to be meaningful. I have a friend who published 17 papers during his 6 year graduate student tenure, and I have a number of friends who published zero peer-reviewed papers during my grad school tenure. Take the numbers with a grain of salt.