Final answer:
The specific duration of Prestero’s team's overseas research for the NeoNurture Infant Incubator cannot be determined from the provided resources.
Step-by-step explanation:
The duration of the research overseas conducted by Prestero’s team before building a prototype for the NeoNurture Infant Incubator is not provided in the resources you've shared. Typically, developing a medical device like an infant incubator involves a rigorous research phase that includes needs assessment, concept development, and user feedback, followed by prototyping. However, without specific information about Prestero's process, we are unable to determine the exact length of time spent on research before prototype development.