Lots of unknowns there.....what are your soil types, yields, tillage system, location?

I no-till/covercrop C-B-C rotation. My normal modus operandi is to add 30#N with the planter. This gives me enough time in case of delays getting the NH3 on. Your putting 5-6#N on with the planter concerns me.....but that is a "here" thing.

I then put the balance of my N on at sidedress (V3-V4 ideally). I average about 120-130#N applied as NH3 depending on the year, price of corn, price of N, how much rain we have had, etc. I have been in the 0.85 #N/bushel range.....but that depends quite a lot on weather. If we have a lot of rain I may bump up the N by 10-15#

I will agree that sidedress NH3 gives you the most bang out of your N $$$$