Purpose: Research on how much early phonemic awareness (PA) instruction is optimal has produced inconclusive answers. We conducted a nonlinear meta-analysis to estimate the optimal cumulative dosage of early PA instruction on PA outcomes with an associated maximum effect size in preschool through first-grade students. Method: Sixteen experimental and quasi-experimental primary studies (35 effect sizes) on PA instruction effectiveness that reported cumulative dosage data were included. There were 613 students in treatment and 542 students in control conditions (Mage= 5.20 years; SDage = 0.87). Results: The cumulative dosage response model took a concave parabolic form (an upside-down U shape). Specifically, PA instruction effects improved with increasing dosage up to 10.20 hours of instruction (dmax = 0.74), after which the effects declined. Moderator analyses revealed these results held for students at-risk for reading disabilities and basic PA skills instruction. Furthermore, moderator analyses showed that the dosage response curves exhibited a convex parabolic form (a U shape) in PA instruction with letters, with effects continually increasing after 16 hours of PA instruction. Discussion: Overall, our findings highlight the importance of planning the optimal cumulative dosage of early PA instruction in preschool through first-grade settings so that students acquire the PA and phonological-orthographic associations taught and show progress in learning to read.