This is the way we like to do it as well. One thing I am unclear on....if the ball is back in the circle prior to the batter making it to first base...does the runner at 3rd have to retreat to 3rd (or advance)??? Or is the play essentially live until the batter/runner stops? I think most of the time the runner at 3rd stays where they were after they took their lead until they see if the pitcher is going to make a play. So...that's my question. And the follow-up would be...will the umpires call it?
UPDATE...duh...wasn't thinking that the LBR doesn't go into effect until the runner reaches 1st. So...I'll edit my question. If the runner rounds 1st slowly and keeps going...does the runner at 3rd have to retreat (or advance) if the P is not making a play on the batter/runner?
The answer to your updated question is YES.