there appears to be (imo) a contradiction in that on the one hand Oswald figures to use his own building as best way to get a rifle in a package to some floor so as be concealed yet when actually goes to the SW window at 12:15pm completely exposes himself holding a rifle in a fully open window, just standing there, holding a rifle "at the ready" position. (per Arnold Rowlands observation).
Then Oswald apparently was startled by presence of BRW at 12:15 such that Oswald must have left the 6th floor and hide on the 7th floor staircase to wait till BRW finally leaves 6th floor. Or where else could he have hidden?
Then Oswald did not go back to the SW window again, which was his 1st choice,and in fact is a pretty good window to get the closest shot at the back of JFK limo, from that 6th floor. Instead he decided go the SE window and for some reason put a box on the window ledge too, and in the end, Oswald exposed himself at the SE window too, to be seen by several witnesses, and even stuck the rifle out the window unnecessarily so far that it appeared to one witness almost 3ft of it visible.
Then Oswald (or other unknown gunman) slowly withdrew the rifle after the last shot fired.
Seems very odd to do all this exposing of himself if he was trying to be stealthy and concealed as per the reason to have chosen his own building so he would be less likely to rouse suspicion from anyone might see him carrying his package.