I spent over 17 years training a 4am at Golds Gym in Venice Beach California. Now I did not think anything about this for there were 20-40 other people in there also by 4:30AM and that included females.
Was I stiff at that time of the morning? Not really but it does take longer to warmup the earlier you start. And you will not be as strong as you will be in later in the day.
But you will also get your workout in each day not matter what for work-Family- etc issues will not be able to intefer with any of your workouts for you will have already got it in before you start your day.
Yes as you get older you will sometimes you need to stay late at work, you have dinner meetings, and Family events which will make you postpone or cancel your workout.
Now for some technical analysis. ! The latest research on your body's circadian rhythms, which are its internal clock, have shown that the peak of several of the most important (anabolic) hormones occur at both 3 and 11 hours upon your awakening. Well, according to science, if you wake up at 5:00 am, you are at your strongest at either 8:00 am and 4:00 pm..
Furthermore according to many strength coaches - such as Olympic Strength Coach Charles Poliquin, your joints like your knees, shoulders, may not be warm first thing in the morning.
What they are referring to is the synovial fluid which lubricates your joints require about 3 to 4 hours to reach an optimal level of warmth which will increase your bodies flexibility. This will provide a increase in athletic performance while decreasing the chnces of injuries.
So if you have the time to train at the 3 or 11 hour upon wakening then you now know it is your optimum training time. But do not worry if you do not. Some of the best bodybuilders and athletes in the world have trained at every hour of the day.