I have 500 acres for grain near Perth, Its very robust and doesn't seem to look hungry like wheat or barley. Personally if I was getting going mid Feb I would just split 3 equal ways, if delayed to march I do it in 2 equal splits. But then I also try and have all N on all cereals before we get to potato planting etc, so finished by mid April. The rooting on rye means that it can capture the N quite well, just need to keep the tillers alive. Max N on the rye is 150kg/ha with 60 SO3. I use inhibitors and I can grow 10t/ha with that level of N on very light soils that would give 9 of wheat using 200kg.