Before-the-Bell: Nortel, Ciena Gain  NEW YORK (Reuters) - Shares of Nortel Networks Corp. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=NT.N target=/stocks/quickinfo/fullquote"&gt;NT.N&lt;/A&gt;  rose 3.7 percent before the bell on Thursday after the telecoms  equipment maker put a specific date, Jan. 10, on when it will  start filing its much-delayed restatement of financial results.