Matter of Gordon, 17 I. & N. Dec. 389, 391-92 (BIA 1980) (because it is more difficult for LPRs who have recently committed criminal acts to show that discretion should be exercised in their favor than for those who committed the same offenses in the more distant past, "common sense and prudence suggest that a recently convicted alien should prefer to let a considerable time elapse before offering to demonstrate rehabilitation.")