First of all, let me preface this by saying that I have no issue with people promoting the idea of God being involved in your life moving forward and His love for His people. However, I must interject for the sake of Scriptural integrity that if you believe Jeremiah wrote these words from a graduation party or after a relationship ended, then you are missing out on what God is actually saying.
Jeremiah 29:11 is not a happy time writing. If anything, this is a writing in the midst of some of the darkest days of the children of Israel. They are in captivity, many of them were suffering as slaves to the Babylonians and many fully believed they would die in this foreign land. Jeremiah spoke to them about God’s plan, but he made it overwhelmingly obvious that the plan did not include freeing them from the 70 years of captivity God had promised. If God is a being of His word (and we know that He is), then the only thing He can be is honest and faithful. God told them they would suffer captivity, but He also told them to build houses, build families and attempt to influence the Babylonians by their conduct.
If you want to suggest that God has a plan for your daughter or son to prosper, I don’t discredit your belief on that. However, may I make a minor suggestion? Perhaps change your focal point from rainbows, butterflies, ponies and constant high points and remind your child that God’s plan is still present even in the pain and suffering that comes with growing up human. God loves you and wants what is best for you.