Deodiaus wrote:

I have a small sidewalk I am working on. The other sidewalks have the
pea gravel & concrete look formed by washing off the concrete before
it sets.
How do I know and when is the right time to wash off the top layer of
concrete to expose the mixed-in pea gravel?
I was told to wait an hour afterwards.

Or two. . . or 20 minutes. It depends on how wet you mix was, how
humid the day is- and what the temp is. Just be forewarned. If
this is your first try you might want to do a test batch and make some
portable stepping stones. [I have a form I built that makes 3
12x12x2 'pavers'. I dump the leftover concrete from a 'real job' in
these squares- sometimes 1, 2, or all 3] They come in handy
sometimes, and make me feel like I'm not wasting anything.

Use a garden hose and broad
broom to lightly remove the concretre.
Any other suggestions?

Don't over wet it- it is an art.

Some have suggested a concrete retardent, but
I could not find any at Home Depot!
Some have suggested a concrete supplier, but said that they carry it
in a 5 gal bucket. Others said that it is not necessary for a small
patch.

I agree you don't need retardant.

Any other things I should know??

Did you prepare the base well? Are you allowing for expansion?
Cracking?

How big is 'small'?
Jim