In my opinion you can own one glider, its like owning one dog. One dog does fine and finds companionship in its owners, but I have 3 dogs now and they also find LOTS of companionship and playtime between the 3 of them.
So a single glider is fine. We have 7 in one cage and 3 in another cage. In the colony of 7 we have one female that doesn't get along with the others at night and I would like to move her out of that colony.
the colony of 3 used to be 2 and 1. the single glider when we got them was scared and acted weird, always hanging from top of cage, doing repetitive motion movements. Once we got her with the other 2 there was a short period she would chase the other female. but after a few months she now acts much more normal, is less scared and plays with the other with no repetitive motion issues, she also now has 2 wheels to play on.
In your situation I would think your schedule would be better to have 2. You say you work at 7:30 am, so you need to sleep early. Who will say hi to only one at 10pm, or 11pm, when they wake up. If you can wake up early and spend some time at 5 to 6 am with a single glider that would be ok, but you wont have them in your shirt sleeping during the day, your at work, at night your sleeping for work. In your situation a pair sounds better for the gliders companionship. If you said you work 2-3 days a week or worked evenings and were home awake at 1 or 2 am, then you would have more time for a single glider.