It's been years since I trained this early. I used to, in my young and (more) dumb days, open World Gym, Campbell at 5:30 am and have somewhere over 400 lbs on a barbell by 6. Crazy crazy stuff and it takes some real insanity to keep that schedule up.
But there really isn't a better time as the hour after I finish work usually does not motivate me to swing volume kettlebells. It is just a matter of deciding to in my mind, and taking the necessary steps( waking up earlier to stretch out and warmup for example) to make it happen.