Because children are more apt to model when they encounter an unfamiliar concept or different situation, modeling will probably be strongest at the beginning of the school year. However, there are principles of modeling that need to be considered daily.
Anderson, P. J., & Reiff, J. (1983). Modeling: An Effective Tool for Teaching Reading. Reading Horizons, 23 (4). Retrieved from http://scholarworks.wmich.edu/reading_horizons/vol23/iss4/10