cabbage question

afternoon all, enjoying the weather  seein as im quite new to growing my own veg this year i went over the top and sowed too many cabbages (as u do  ) im too embarrased to say how many iv sown but there is only too of us and soooo many, my question is... my cabbages (stonehead) are gettin really big and beautiful now, the leaves are lovely and green  can i start to use these now? even tho theyre not due to be harveste autumn time??? what would be the harm? cheers folks x

thanks so much for that