My Black Australorp JUST started laying two days ago and is the same exact age as your RIR. I also have an Easter Egger that's one week behind her that has yet to lay. My Australorp suddenly did an egg crouch for me when I was reaching over her last week (and man did she look surprised!) keep an eye out for your RIR to give signs like that and getting more vocal and red in the face. Waiting takes forever, but getting that first egg is so exciting.