How many sentences long should the story be?

Here are the words I'm focusing on: flock, crop, plan, flat, west, snap, hint, cluck, blush, ranch, skip, pluck, kept, bench, clap, fled, chimp, small, mask, crush, pinch, band, punch, chomp, pump, clip, mint, tilt, gulp, self, grass, fluff, class, dress, press, still, belts, cliffs, drills, sniffs, champs, drops, ponds, pests, dents, stubs, grips, clocks, plugs, drums, vests, steps, flags, drags, drips, flips, tests, clicks, frogs, swims, say, says, see, between, each

Is there anything else I should consider (e.g., focus on using words with certain digraphs, blends, or whatnot, include a theme or topic)?

David has a small ranch. He kept a flock of hens. Each day, he feeds them with a crop of grass and bugs. David loves to hear them cluck and see them peck. One day, a frog swam into one of his ponds. David grinned, clapped his hands, and said, "What a surprise from my ranch today!" ---