In the beginning, doing meditation just once is fine, but make sure you do it right after asanas and pranayama. I could fit in only one session for the first six months.
If you do want to add it to the evening routine, it is recommend to do it early, and not close to bed time (as you mentioned in your post above) as it may interfere with your night sleep. It does not affect everyone, I can do it close to bed time and sleep well after, but some people cannot sleep after meditating close to bed time.... so it's individual. You can try it and see how you react to it.
The one thing to keep in mind is to rest after meditation. If you are doing it close to bed time, rest, then get up and do something, like watch TV, read, walk around a bit, then go to bed. If you fall asleep directly after meditation, it can make you groggy and tired the next day.
Wish you all the best. Hope some of this helps.
PS:Yes, the author is a very generous and loving soul. Blessed to have him in our lives.