About 1 hour to 1 hour and a half from the starting point at the parking lot discribed at Mont Fitz Roy pinpoint, depending on your pace.
PRO TIP: Try to reach here from 8h to 9h, also depending on the time of year, to take gorgeous pics of the first rays of sunlight hitting the pale stone wall of Mont Fitz Roy. The photo I'm using here was taken by me, on October 21st at 8:28am