Thanks for posting those pix.
Wow, that might me a bit much to be top dressing. How long long technically is your growing season? If it's until October, my math tells me you'll be putting 4 inches? Yikes!
I'm no expert with warm season grasses, but does this seem excessive to anyone else?
Seriously, I admire your plans for such hard work! I seriously doubt you'll need fertilizer!
Looks great, nice work!