I believe moderate (not intense) morning exercise should contribute to good cardiovascular health. As for the spine, perhaps morning would require a little more attention to a warm-up period, say a few minutes of stretching and slow walking before the bicycle or fast walking.
That's how I see it.
Since blood is sent preferentially to the gut after eating--for the sake of digestion--moderate exercise before breakfast would theoretically be better in terms of blood irculation to the muscles.
No problem with exercising with 'swollen' discs: They are actually a bit plumper after a whole night lying down (counteracting gravity), and that just means that the spaces between the vertebrae are a bit wider--which equals a more comfortable back.
Drinking green tea will give you a tiny, tiny bit of caffeine, which could make you feel perkier. However, the water it's dissolved in also means you'll have to urinate more.
You've been useful ;)
Anybody else who has something to say regarding this issue is welcomed to do so.