The research on timing is difficult to summarize because the conclusions about timing in early childhood are inconsistent. Depending on which outcomes are of interest, the type of intervention, and the sample being studied, the role of timing is more or less important. Additionally, it's important to note that timing is rarely the sole focus of any study; therefore, there are many other factors that cannot be ruled out as potential confounds. Only one study was identified that used an experimental design to examine the importance of timing in an early intervention program aimed at improving maternal responsiveness (Landry, Smith, Swank, and Guttentag, 2008). Consistent with the general view regarding the importance of timing in the field, Landry and colleagues concluded that the optimal timing of the intervention depended on the specific type of behavior being intervened on and the changing developmental needs of the child. In other words, if an intervention to improve literacy outcomes is focused on children's phonological awareness, it would be futile to intervene with infants or toddlers as phonological awareness doesn't develop until preschool. An intervention with infants and toddlers that is aimed at improving future literacy outcomes may want to focus on increasing the amount of time parents spend reading to their children, a developmentally appropriate activity for infants and toddlers. There has been a great deal of interest in examining timing with regards to the entry into early care and education programs as well. Again, the literature is somewhat mixed, with some studies finding that earlier entry into childcare is related to improved child outcomes (Creps & Vernon-Feagans, 1999; Doyle, Harmon, Heckman, & Tremblay, 2007; Harrison & Ungerer, 2002) and other studies finding that earlier entry into childcare is related to poor child outcomes (NICHD Early Child Care Research Network [ECCRN], 2002). However, once child care quality is taken into account, the relation between early entry into childcare and poor child outcomes are most often mitigated. Still, when considering timing and child care, the type of outcome being examined, the developmental needs of the children at the time of entry, and the quality of the intervention are highly relevant to whether or not children demonstrate improved outcomes. Therefore, program developers, researchers, funders and policy makers must be clear on the developmental importance of the behavior or behaviors being focused on for the age of the children they intend to serve.
CEED Editorial Statement: Intervening earlier is generally better, especially for programs serving at-risk families and children. There is no one ideal age at which interventions should occur, but when a program is aimed at improving the whole child, and does not have a specific outcome or behavior being targeted, infancy seems to be ideal. If the program is intervening on a specific behavior/skill/quality or has a specific outcome in mind, then the program should begin in the developmental period in which the behavior/skill/quality begins developing.