Hugh Chester-Jones at the University of Minnesota Southern Research and Outreach Center summarized their research data on calf starter grain intakes. These data are for many trials over a number of years.
The intakes are reported for two-week intervals from day 1 to day 42.    
  Daily Intake during 2-wk period
Ave Oz. Low Oz. High Oz.
1 to 14 1.9 0.9 3.0
15 to 28 13.7 10.1 18.1
29 to 42  33.9 28.1 39.1

[See at bottom for these data in metric grams]

I changed these numbers into percentages so I could see more easily the amount of variation of the low and high calves compared to the group averages.

  Percent of Average Intake for Low and High Calves
  Daily Intake during 2-wk period
Age Ave Oz. Low Oz. High Oz.
1 to 14 100% 47% 325%
15 to 28 100% 73% 180%
29 to 42  100% 83% 139%

No wonder it is so difficult to answer the question, "How much starter are the two-week old calves eating?" Well, it depends on the calf!

Worthy of note in these data is that the percentage variation among calves does decrease as they get older. Still, if we wean a group of calves based on "average" intake there are likely to be a significant number of calves that are well below our threshold consumption level.
My take home message? 
Among individually-housed calves I continue to believe that it is worthwhile to observe the variation among starter grain intakes. When raising my own calves in hutches I always identified the "laggard" calves. 
Among the younger "laggard" calves, I checked them again for a navel infection. When I started the weaning process for 5-week-old calves by stepping-down the volume of milk replacer fed I often waited an extra week on full milk for the few "laggard" calves that were eating far below the average amount of grain.
Reference: Hugh Chester-Jones and Neil Broadwater, "Calf Starters", proceedings of Minnesota Dairy Days, 2009. p.9
For those who are more comfortable in grams, here is the first table in metric.
  Daily Intake during 2-wk period
Age Ave Grams Ave Grams Ave Grams
1 to 14 55 26 84
15 to 28 389 285 512
29 to 42  963 798 1109