In wireless sensor networks (WSNs) applications such as environmental monitoring, it is essential to design protocols that are energy efficient and that are scalable. The main technique to reduce energy consumption is to use a duty-cycle, where nodes periodically go to sleep. However, the implementation of such a duty-cycle often requires nodes to be synchronized, which is difficult to achieve in a scalable manner. In this paper, we study the delay of blind rendezvous for unsynchronized nodes, that is the delay required for two unsynchronized nodes to be active at the same time. There are several major advantages of blind rendezvous: nodes do not need to share a prior knowledge, nodes do not need to be synchronized, and the support for network dynamicity (due to node mobility or failure) is simplified. We show through simulations that the delay to achieve a blind rendezvous is reasonable in many scenarios.