You should generally wait at least 2 to 4 weeks before mowing after overseeding your lawn. This allows the new grass seedlings enough time to germinate, develop roots, and establish themselves. The new grass should be about 3 inches tall before the first mow, and when mowing, use the highest blade setting to avoid stressing the young grass. In some cases, waiting up to 5 to 6 weeks may be necessary, especially for warm-season grasses or slower- growing grass types. Weather, grass type, and soil conditions also influence the ideal timing for mowing after overseeding. Shorter waiting times, like 4 to 7 days, are sometimes suggested but risk damaging the new grass if roots haven't developed fully.
