There's no one best time to meditate. Many people find it useful to get up a bit early and meditate before the pressures of the day mount up. They want to prepare for the day so that things go well. Other people like to meditate before going to bed in order to "unwind." Both can work.
I'm far from being a "morning person," but I prefer to meditate before breakfast. Maybe it's not a good idea for us to limit ourselves with these labels -- "morning person" and "evening person." Even those of us with allergies to mornings can benefit from getting up a little early. The beneficial effects of twenty minutes of meditation before hitting the streets usually far outweighs the benefits of another few minutes in bed.
You might even want to experiment with meditating during the day. You could try shutting the office door, taking the phone off the hook, and catching ten to fifteen minutes of relaxing and stimulating meditation.
And there's no reason why you can't meditate more than once!
Choosing a Time
Probably the worst thing you can do is to tell yourself that you'll just "fit it in" at some point. That point will probably never come. You need to decide when you're going to meditate and stick to that time. If you plan your week, then plan your meditation into your week to make sure it happens. It's too important to leave to chance.
Places
Although I've suggested that you can meditate anywhere, like the office, it can be good to have a particular place to meditate regularly, and to make that place a little special, meaningful, and beautiful. You can do this by having some pictures that remind you of why you want to meditate - whether religious imagery or natural imagery. You can have candles and incense. I find that the ritual of "lighting up" is quite soothing and grounding, especially if I do it with mindfulness, and in a spirit of reverence.
