Answered by Steve, Hiring Expert at Caterpillar Inc., on Friday, October 18, 2013
It does vary by company, but in the case of Caterpillar, we begin to recruit for interns in the fall of year prior to the internship. For example, right now we are recruiting for spring, summer, and fall 2014 internships. Therefore, my recommendation is to begin preparing up to a year in advance of when you will be available for an internship. Temporary jobs are different in that these are mostly filled through agencies/contractors and a recruited for 30-60 days in advance of the need.