How long until US troops fight directly against ISIS?

A valid question which deserves a proactive answer.

CPT Maurelli, I'm guessing that within 4-6 weeks, our advisory forces in Iraq will be drawn into direct contact with ISIS forces.  I'm basing this primarily on today's probing activity at Al Asad, and the fact that ISIS now occupies the village of Al Baghdadi, approximately 20 Km away from Al Asad.  

It seems that ISIS has turned up the level of intensity since the burning execution of the Jordanian fighter pilot.  With the death of Kayla Mueller, ISIS lacks U.S. hostages. It is my opinion that the prospect of engaging a small number of U.S. forces will embolden ISIS, as they see this a direct strike against the great satan.  The impetus behind striking these small advisory forces however, are two-fold:  one, they will further disrupt and demoralize reconstituting Iraqi Security Forces; two, the opportunity to capture U.S. Military Personnel would provide ISIS a strong recruiting, PR, and financing boosts while embarrassing President Obama and discrediting U.S. foreign policy.

I could be wrong, and I hope I am.  This is just what the mouse on the wheel in my head is generating based on the events of the last couple of weeks.

Not long...