The answer seems to be no, you can’t sort by date in the BNC. If anyone knows otherwise, then I’d be interested!
You might get a date for a specific hit by clicking on it though this may end up being “(1985-1994)” which is useless for any purpose I can think of. When that happens I try to see if Google can find the context by searching for part of the excerpt in double quotes, though this is hit and miss.
What I can tell you is that other BYU corpora do have a way to group by date. You just go to the chart tab and “see frequency by section” and your results will be broken down by into time frames. (Sometimes it’s not granular enough though so you would have to search through a bunch of hits to find the earliest, but it’s there.)
Only some of the corpora will do this, such as COCA, COHA, and Hansard. Other times, as is the case with the BNC, the chart will use some other metric, such as spoken vs academic vs other types of English.
In fact I researched for this etymology answer by searching EEBO via the BYU website. In the case of EEBO, there is another website that I was using before that I liked better for a number of reasons, but you can’t use it without a subscription. Some of the other corpora may also have other ways to access them, though I don’t know if any.