The objective of this paper is to study the transient distribution of the buffer content in any intermediate node of a wireless network based on IEEE 802.11 standards. The steady state solution of the discussed model has already been given in Arunachalam et al. (2010). The methodology used, maps the underlying model to a fluid queue model driven by two independent finite state birth-death processes with the aim to simplify the solution which is obtained in closed form with numerical illustration. Along with the buffer occupancy distribution, other performance measures: throughput, server utilisation and expected buffer content are also obtained numerically.