i was using the wave equations (without time dependency) to calculate the votlage on a specific point (z=zo) on a transmission line.

My question is, to which time point is my answer valid? Like the answer i am getting by solving the wave equations is for t=? Do i consider t=0? But i am assuming that at t=0 the wave still didn't propagate which is making it for me not understandable. Any help??

Thank you!!!