I started at 9:00, the drawing took 3.5 hours. By 5:30 I had 100% coverage, the cardinal had flown into the picture "Paint the bird before it flies away", and I have gone over the error areas with the first coat of white. I'll get the second coat where it needs it tomorrow.

Day 2, The decision is made, morning shadows it is. In addition to the normal darks being made with magenta and green, blue and brown (dark yellow is brown), cyan and red, I am using a secondary complementary pair that are both opaque colors. They wont give a really dark dark but it is neutral and does make a nice neutral, warm and cool gray. That would be Cobalt Blue and Cadmium Orange.
By 3:16 the shadow areas had reversed themselves from their 9:00 positions. The changing shadow areas are making the object edges apparent. That's the good side so I concentrated on making 5 distinct distances. Distances are marked on concentric rings around you. The darks in the closer rings have to be the darkest. Aerial perspective is a variable scale, the darks should change lighter and bluer in each ring as distance increases. Click that link to see how to mix those colors.
6:43, done for the day, cleaned up by 7:00. 

Day 3, 8:30, Full palette loaded with a full days supply. 10:07 I've changed about 30% of the shadow areas to match this precise time of day. 11:04, Ten minute break.
1:02, Heading to the home stretch, I've just gone over the entire picture adding white to correct errors, highlights, weeds and changes in general. Green Gold is the cool transparent yellow, Indian Yellow is the warm transparent yellow, they are both good for glazing.
3:35, Hopeless ... I have to stay another day on location. I'm having trouble with the edges of one concentric ring.
4:49, Well I can see where I can get it done tomorrow but I'm not done today yet. Take a break then start cleaning it up again.

Here are the brushes I am using.
#12, style 14, Delta, a 3/16", a round ferrel flat end sable with 7/8" long hair. Also a 3/4" length and a 5/8" length.
'Shorty', 1/2" long round ferrel, flat end sable. Another great brush that isn't made anymore.
The sign painter's art is fading out, and with it the brushes that had great stroke control. The most useful brushes I own are not in anyone's catalog.

Day 4. 7:00, last day. I should have done this in water colors. I would have been forced to outline each pattern. You must be able to pick and choose which objects are in the sunlight and which are in the shadows.
9:30 break. I feel good, I'm getting it. BR>10:30, my most distant shadows are too dark, I have to lighten them up to get the feeling of a receding distance.
1:00, Finished! 'Paint the Bird Before it Flies Away.' Hosgrove Park, 7,000 foot elevation. Six hours today did it, I'm glad there was no rush.
3:58, the final varnish, polyurethane water based is on and I'n on the road again.