Multiple studies and systematic reviews have shown that music instruction improves phonological awareness (PA) and early literacy skills in children, although findings vary. In meta-analyses, the reliability and significance of the transfer effect are reduced. The study evaluated the effect of varying durations of music instruction exposure, over a single academic year, on PA and early literacy of young children. Based on the exposure to music instruction, participants were assigned to either a low- or high-exposure group. Additional analyses were conducted for 17 age-matched pairs and to compare participants that only received class music to those that received additional music instruction. Between-groups comparisons showed no significant difference after a single academic year of music instruction. Within-groups comparisons identified more PA improvements in the high-exposure group. Exposure to music instruction for no less than one academic year, is required to conclusively evaluate the effect on PA and early literacy.