Beginner question, why is now a better time to apply N than at planting? Assuming you have rain coming to keep it from dissolving.
Or, is it good to apply multiple times in increments instead of loading it down at one time?
Not sure that now is a better time to apply than planting. You need that initial fertilizer to get your plants up but eventually all of those nutrients are either used by the plants or leached out of the soil from rain and other factors.
After the first 60-90 days I like to reapply some Nitrogen to get the plants to continue to put out top growth which is what the deer are eating for the most part. This time of year with lower soil temperatures and slower growth you shouldn't have to put out as much fertilizer as you would at planting because it isn't being used up and broken down as quickly.
Your plants should tell you when they are becoming deficient by how they look. Yellow leaf tips is usually a sign of a nitrogen deficiency.
I want as much biomass as I can get right before it turns cold and the rut to hopefully bring in some deer to my fields and property. Healthy fields attract deer better than weak fields.
The rain should make your nutrients more soluable and easier for the plants to uptake.