Explain what the risks of friar laurence’s plan might be? what is an essential component of the plan?

Friar Laurence's plan relies on perfect timing and communication. Romeo needs to get the message of the plan in enough time to make it back to the tomb and meet Juliet as she wakes up. 

There are several things that could go wrong including Romeo not getting the message or Juliet waking up too early and her family knowing that it was a trick.