In 2005, Apple announced a split on Feb 11announced a split on Feb 11...
CUPERTINO, California — February 11, 2005 — Apple® announced today that its Board of Directors has approved a two-for-one split of the Company’s common stock and a proportional increase in the number of Apple common shares authorized from 900 million to 1.8 billion. Each shareholder of record at the close of business on February 18, 2005 will receive one additional share for every outstanding share held on the record date, and trading will begin on a split-adjusted basis on February 28, 2005.
...one month after announcing earningsannouncing earnings.
CUPERTINO, California—January 12, 2005—Apple® today announced financial results for its fiscal 2005 first quarter ended December 25, 2004. For the quarter, the Company posted a net profit of $295 million, or $.70 per diluted share. These results compare to a net profit of $63 million, or $.17 per diluted share, in the year-ago quarter. Revenue for the quarter was $3.49 billion, up 74 percent from the year-ago quarter. Gross margin was 28.5 percent, up from 26.7 percent in the year-ago quarter. International sales accounted for 41 percent of the quarter’s revenue.
I wouldn't expect Apple to offer another split, as it's become somewhat fashionable among tech companies to have high stock prices (see GOOGGOOG or NFLXNFLX or even BRK-ABRK-A/BRK-BBRK-B). Additionally, as a split does nothing to the underlying value of the company, it shouldn't affect your decision to purchase AAPL. (That said, it may change the perception of a stock as "cheap" or "expensive" per human psychology).
So, to answer your question: companies will usually announce a stock split after releasing their financial results for the preceding fiscal year. Regardless of results, though, splits happen when the board decides it is advantageous to the company to split its stocks.