The distance your joists can safely cantilever or overhang a drop beam is determined by the size of the joists, the wood type and grade of the lumber and the spacing between joists. Many building departments limit joist cantilevers to 24" maximums. You must use at least 5 framing nails to attach the rim joist to the ends of your joists.
The Wood Frame Construction Manual, Published by the American Wood Council states that cantilevers are limited to 1/4 the span of the joists. 2x10 joists spanning 14 feet, for example, could cantilever up to 3.5 feet.