Got my sex links as pullets so only have approximate hatch dates. The RSL was a bit older and already laying. She's an absolute machine, gives me a huge egg about 6 days a week. The two BSL's were of "laying age" when I got them the end of June. I was told they should start laying "any day" and they'd been born in March. Well, they hung on and didn't begin laying until August! For a while there I was afraid they were roosters!
While I don't have any definite number of weeks for you, don't be surprised if the black ladies take longer than the red. They seem to do things differently, too. Although younger, the two BSL's went through mini-molts in January/February. The older RSL hasn't dropped a feather yet. The RSL laid well all through winter, the two BSL's came to a halt when molting began. One is over it and is laying again. The other has yet to resume laying.