I saw a commentary about the second three and a half weeks.  See Doug Batchelor at AmazingFacts.org  "Solving the Messiah Mystery Part II" It was Wednesdays broadcast....you can view it at the website.  About two thirds into the commentary he talks about the second three and a half weeks.He states that the covenant was confirmed by the apostles because for three and a half years they only preached to the Jews.  At that point Stephen was martyred and Saul was a witness.  He converted at that point and that is when the gospel began to be preached to the Gentiles. Batchelor feels the seven years were fulfilled.  The covenant was only for the Jews.

Hope this helps....Keep looking up!

In HIS hands....April