When an enterprise system is introduced, system users often experience a performance dip as they struggle with the unfamiliar system. Appropriately managing this phase, which we term as the swift response phase (SRP), is vital given its prominent impact on the eventual success of the system. Yet, there is a glaring lack of studies that examine the SRP. Drawing on sensemaking theory and early postadoptive literature, this study seeks to propose a theory-driven model to understand how different support structures facilitate different forms of use-related activities to induce a positive performance in the SRP. The model was tested through a two-stage survey involving 329 nurses. The results demonstrated the discriminating alignment between information system (IS) use-related activity and support structures in enhancing system users’ work performance in the SRP. Specifically, suitability of impersonal support moderated the effects of standardized system use and individual adaption on performance, whereas availability of personal support only moderated the effect of nonstandardized system use on performance. For moderating role of personal support, IS specialists support had a lower influence than peer-champion support and peer-user support. This study contributes to the extant literature by (1) conceptualizing the turbulent SRP, (2) applying sensemaking theory to the initial postadoptive stage, (3) adding to the theoretical debate on the value of system use, and (4) unveiling the distinct roles of support structures under different types of use activities. Practical suggestions are provided for organizational management and policy makers to deal with the complexities in the SRP.