ECEC settings are children's first contact with early education, and ECEC teachers are expected to encourage and support children's early literacy development. This study aims to pilot test the self-assessment tool Social Language Environment -- Domain, (SLE-D), in order to gain more knowledge about teachers' strategies when teaching literacy. Fifteen ECEC teachers used the tool as a support to focus on didactic strategies that provide conditions for children's early literacy development over 22 months. The data consists of (N = 299) self-reported and rated teaching activities across four time-points. Cronbach's alpha showed satisfactory internal consistency for the entire self-assessment tool, while each domain showed somewhat lower levels of consistency. Principal component analysis suggested a 5-factor solution, indicating subdimensions of the three dimensions. However, item mean values showed notable changes in ECEC teachers' ratings, which can be interpreted as teachers developing their strategies in literacy-related play activities by using the tool.