The color started about 5:43a, which is about 20 minutes before official sunrise. Here's how it began:
Three minutes later (5:46a) it was warming up:

And the color began to spread (5:51a):

The peak of color arrived three minutes later (5:54a), still well before official sunrise:

Then it started to fade:
5:58a

6:02a

Ten minutes later (6:13a), the clouds had pretty much all gone to gray, but interesting patterns were beginning to form:

At 6:24a, the temperature dropped a couple of degrees, and the light fog that had been floating just at the surface of the water suddenly became a thin veil of fog 10 - 20 feet high (see especially the big cloud on the right side of the image):

The fog receded quickly, but the cloud patterns kept evolving (6:40a):

Just about an hour had passed since the initial glow. A few hours later the first wave of overcast from Hurricane Irene (still over 500 miles away) filled the sky.
If you would like to see the images above in a larger size, click on the following link:
Ten Minutes of Awesome Sky