As others said put it on now.  If you need it you need it.  In the right year here 5.2 is doable on soybeans but it seem like a year of corn with the nitrogen applied will cause it to need another ton if resampled in the fall.  The only way we don't put it out when needed is if we just can't due to weather and then it goes to beans for sure till we can hopefully get it the next fall.