Do you Realize that he that he never really knew his son ever. Then travels through time only to find out his son dies and grew up thinking his father ran out on him. and John will never know that his dad died saving his sons!
Oh my gosh, so sherlock must of met the doctor! How else would he go back in time. He must just call himself Benedict Cumberbatch like the doctor calls himself John smith, a cover. The name "Sherlock" would attract to much attention.