When foot is the main means of transport, one day's journey might not be all that far - depending on trail/road/weather conditions, of course, and on how straight a line the trail/road takes.
Horse-and-carriage or horse-and-wagon isn't much faster if any. Horse alone can be, but not by as much as you might think over the long haul.
In good conditions on reasonably flat terrain, making 20 miles a day is probably the best you can hope for without exhausting yourselves or your mounts. In less-than-good conditions you won't even get that far.