I used to write in the morning after a good breakfast. It worked well. But life changes and what worked then does not work now.
I can not write in my usual time because I moved to a new city and for whatever random reason there always seems to be something I need to do in the mornings after breakfast. It really has nothing to do with the new city, but more to adjusting to a new life. Old habits are hard to break, and I always wrote first because when I had a good day I could reward myself in some way. But that is a big problem. Why reward myself after doing work, why not before?
On a flight to London many years ago the flight attendant brought the dessert around first. It was strawberry shortcake, one of my favorites. I was hungry with a capital H, but I held off and waited, and waited, and waited while listening to my gurgling stomach. But after half an hour of waiting I ate my strawberry shortcake. When the flight attendant returned I was chastised for eating my dessert first. I remained calm, resisting a smart aleck comment that I am known for, but politely said I was starving and could wait no longer for the meal. Today just to spite this unknown attendant I sometimes have desert first.
I think this incident affected my reward system. Have fun first then work. It works better for me. Now I write later in the day before dinner. I can write through dinner, then reward myself after a good day of writing. No reason not to reward yourself twice in one day.
The point is not to fall in love with your schedule as life changes and sometimes you must adjust when things change. Write when you have the time away from distractions, have healthy snacks. I eat a mixture of sliced almonds, walnuts, and raisins. There is also a bowl of grapes and bottled water, with a no calorie flavor enhancer.
My e-novels written during the morning days are found here: http://www.amazon.com/Terry-Nelson/e/B00EEVHN38