Jane, I started taking glycine 2-3 weeks ago, one 500 mg capsule on an empty stomach 1-2 hours before bed. I saw improvement right away. My sleep quality was better and I was sleeping somewhat longer, but not long enough. I added a second 500 mg cap in the morning and my sleep improved again. It's still not quite where I'd like it -- I need to sleep longer -- but the quality is much better.
Instead of the second 500 mg in the morning you could take 1000 mg in the evening.