Mobile data demand is increasing tremendously, and thus new pricing models are in urgent need. One promising new pricing scheme is the “sponsored data plan”, i.e., end users may enjoy free access to contents from certain content providers, while these content providers will pay ISPs for corresponding traffic consumed by end users. Proven a number of advantages, the sponsored data plan is still in its infancy. In this paper, we explore some potential of further development of this plan. We extend the design space and propose the idea of time-dependent, sponsoring, i.e, content providers can decide when to sponsor how much fractions of traffic. The key intuition is by migrating some traffic consumption from peak to valley times, bandwidth resources can be better utilized. We formulate a game model to study the interactions between the ISP, CPs and users, and derive the optimal sponsoring fractions over various times under this new plan. We show that all parties involved can benefit from this plan, and social welfare increases. We believe our proposal, i.e., time-dependent sponsoring, provides important insights to potential development of the sponsored data plan.