When to Use a Delayed Steal
A delayed steal is called when the pitcher and catcher are doing a poor job of watching the runner on 1st, or the middle infielders are not doing a good job of picking up 2nd base. Executing a delayed steal starts with taking an aggressive leadoff. When the catcher releases the ball to the pitcher, the runner breaks for the next base.

The base runner must be fully committed to doing this and always go in sliding (preferable sliding by and reaching around to touch the base).  This is always a tag situation, so that extra .5 of a second will almost always result in a successful steal attempt.