Pistol grip or French grip, and when should I switch?

Start on whatever your club starts you on (usually French for beginners, and always French in many youth programs), and don't rush the switch, the grip question matters much less than beginners think, and much differently than they think.

The actual difference: a pistol grip locks your hand into one strong, fixed position, more blade control and strength for close bladework, which is why most foilists and many épéeists end up there. A French grip is a straight handle with a pommel, less locked-in strength, but it allows 'pommeling' (holding it at the very end) for several inches of extra reach, which is why a whole school of épée fencers stays French forever and wins by fingertip.

When to switch to pistol: when your coach says your point control is ready, typically after a year or two, once your fingers (not your wrist or arm) are doing the bladework. Switching too early hides sloppy technique behind the grip's strength; that's exactly why youth programs mandate French.

When to stay French: if you're an épéeist who likes distance games, counterattacks to the wrist, and defensive fencing, the long-French-grip style is a genuine competitive identity, not a beginner phase. Foil and sabre are simpler: sabre has its own grip, and virtually all serious foilists go pistol eventually.