When to Review Code

I am assuming I can take it for granted that most developers acknowledge the value of performing code reviews. All the companies I have worked for have had some kind of policy that states a code reviews must take place, but when the code review takes place can vary dramatically. While I was writing this post, I came across a couple of helpful Stack Overflow questions which have more insights on the when a code review should take place. I'll discuss three possible times to perform a code review: