It seems to be pretty well accepted that early identification and treatment of calves with pneumonia is a best management practice.

The guide developed by Sheila McGuirk (Univ. Wisconsin College of Vet. Med) has been very useful for me. See THIS link to find that guide for observing individual calves. 
When observing calves in individual pens or hutches I just assign one row on a ruled tablet to each calf. As I look at the calf I mark down her nasal and eye score as well as a scour score. After I finish walking all the calves I make a crude summary at the bottom of the last page counting up scores for all calves. That is, how many 0's, 1's, 2's and 3's for the whole population.
Today I found the group observation sheet at this site. Click HERE for this sheet. That way one can summarize scores with one row per pen. Dr. McGuirk suggests counting the number of abnormal scours (2's and 3's) for each of four observation points. She suggests the goal of less than 25% abnormal scores on any point. 
These scoring guides have been helpful in my consulting work as a way to teach the calf care personnel to observe calves. Each time a person visits the individual pen or hutch they have the opportunity to spot abnormal eye or nasal discharge. Bedding is a good time to observe for the calves as they are active jumping around - which ones are coughing?