There have been stories where Lois and Clark cross paths earlier ranging from teens to just before he came to Metropolis. What if they were at the same camp as teens and lighting struck. If there were several days of bad weather so no sunshine Lois might not notice her powers until she has been home a couple of days. Add in that clark didn't have all powers until late teens and she might take a week or more to realize. High school Lois with super senses and a realization that she is hard to hurt would do a lot of snooping. When the flying kicks in she would be a lot mor obvious then Clark so he would be the second one to go public. Once he sees how she is received I'd expect he'd follow quickly.
