Meditate when you can
When I woke up this morning I wasn't in the mood to meditate, possibly because I didn't have the time for it. It was a Monday morning, cloudy, and snowing, and I just didn't feel like getting out of bed. By the time I got up I had to get to work almost immediately. So I didn't take any time to meditate.
But then later in the day I did feel like it, so I took a little break and sat down for a fifteen minute session. I don't skip morning meditation sessions too often these days, but when I do, I almost always make up for it later in the day like this.
On mornings like this I'm sure it helps to live in a Zen Center (where other people will help drag your butt out of bed), but assuming you don't live in a Zen Center, if for some reason you can't meditate at your usual time, meditate when you can.