Hello.  My question is where to locate the two 4 x 4 support structures I am going to use beneath a garden window which is suspended off of the house. 

I would like to position them at an angle from the bottom of the garden window to the house with lag bolts.  The dimensions of the garden window are 72 inches wide by 30 inches high by 24 inches deep.  The 24-inch dimension is the portion that extends from the house.  Thank you.