The occurrence of time processing problems in individuals with Development Dyscalculia (DD) has favored the view of a general magnitude system devoted to both numerical and temporal information. Yet, this scenario has been partially challenged by studies indicating that time difficulties can be attributed to poor calculation or counting skills, which can support reasoning on time in school-aged children and adults. Here, we tackle this debate by exploring the performance of young children before they fully develop the symbolic number system. Preschoolers at risk of developing DD were compared with typically developing children in a series of tasks investigating time processing and in their 'sense of time', evaluated by parents and teachers. Results yielded a poorer performance in time reproduction of 5-second intervals and in time discrimination, as well as a weaker 'sense of time', in children at risk of DD. These findings provide evidence of a common magnitude system that would be responsible for deficits in both numerical and temporal domains, already at early stages of life.