  Consider the random process in which the edges of a graph $G$ are added one
by one in a random order. A classical result states that if $G$ is the complete
graph $K_{2n}$ or the complete bipartite graph $K_{n,n}$, then typically a
perfect matching appears at the moment at which the last isolated vertex
disappears. We extend this result to arbitrary $k$-regular bipartite graphs $G$
on $2n$ vertices for all $k = \omega \left( \frac{n}{\log^{1/3} n} \right)$.
  Surprisingly, this is not the case for smaller values of $k$. Using a
construction due to Goel, Kapralov and Khanna, we show that there exist
bipartite $k$-regular graphs in which the last isolated vertex disappears long
before a perfect matching appears.
