Porphyry Cu-Au deposits develop by a complex series of overprinting events of intrusion emplacement, hydrothermal alteration and mineralisation, which by development to varying degrees in each system, contribute towards great variations between individual porphyry deposits. While most porphyry geological models represent the end result of these overprinting processes, porphyry deposits can be better understood in the exploration environment by the consideration of time such as in the staged model for porphyry development (figure 1). Exploration of the Philippine magmatic arc geothermal systems in the 1980s provided Terry Leach with the opportunity to view many porphyry Cu-Au intrusions at varying stages of development, including the relationship with magmatic arc epithermal Au-Ag mineralisation (Mitchell and Leach, 1991). The application of those geothermal studies to Cu-Au mineral exploration in the SW Pacific rim in the early 1990s facilitated initial development of a staged model for porphyry Cu-Au development (Corbett and Leach, 1998), which further evolved by application to porphyry systems in other magmatic arcs (Corbett, 2008, 2009; 2017 & 2018).The exploration implications of the understanding and application of this staged model for porphyry Cu-Au development lie in the use of vectors within wall rocks towards blind porphyry deposits and the interplay between mineralised and barren events. Variable geophysical signatures which result from overprinting events of porphyry intrusion, alteration and mineralisation are better interpreted in a context of time. CITATION: Corbett, G J, 2019. Time in porphyry Cu-Au development exploration implications, in Proceedings PACRIM 2019, pp 177180 (The Australasian Institute of Mining and Metallurgy: Melbourne).