African guinea fowl are sexually mature at around 6 or 7 months . When the start to lay eggs will be another matter. Guineas are seasonal layers. They will only produce eggs during the spring and summer months. So if they become sexually mature in the Fall say October they usually won't come into lay until the following Spring.
Another site said they will lay an egg a day in season, but that many guineas might share the same nest meaning a few eggs a day might show up.
Hope that helps. I don;t have any, but I'd love to have a flock someday