Stocking rates (number of animals per acre) high enough to keep up with the grass growth rate this time of year would be too high for when the grass growth rate slows later in the summer. I'd rather have too few animals now, than too many later and then watch my fields get grazed down to the soil, sell animals, or feed hay.
The plan had been to cut this field for hay; all our rain has delayed making hay. As it turns our there is sufficient grass in the other fields (which are easier to cut) so that this field will just get mowed but not until after all of the hay has been put up.