OK here's the basic idea with a couple of facts.
1) 3 Shang foragers gather 27 food every 20 sec
2) 4 Shang foragers gather 36 food every 20 sec
3) It costs 35 food every 20 sec to keep producing Shang vils
4) If you are running low on food and have to HC each new vil at the last second or after the preceeding one was born you usually lose a couple of seconds in lagging zone games.
5) Shang normally has enough food in Q for a couple of extra vils once you start foraging
6) An extra wood chopper early on means that you can pit and then dock faster and those earlier FB will start gathering food to help you tool
I posted about all of this when I discussed my Shang Super Boom a few months ago. What all this means is that assuming you find berries quickly as Shang you use only 3 foragers while you surplus food depletes at a rate of 8 food every 20 sec as you produce new vils. When it looks like you are going to be running low on food (typically vil 10-12) you send the necessary 4th forager to the berries. This mean that you pit faster and can easily function to create a forest wood pit and your houses with only 2 strags. Even with mediocre strags I can build that pit typically when vil 10 is born. If I am short wood I can wait to build the house at the last minute with 2 vils after #11 is born. I have found that this is the best way to crank up a boom with Shang and when well done with good fishing you can simply boat boom while pumping vils all the way until you click the tool button between 8 and 9 minutes with 27-30 real vils and many FB from 3 or 4 docks. Your only land based food gatherers are the 4 foragers. Arriving at a 10-11 minute tool with the food to bronze jump and the wood gathering capability for a navy soon and wood/gold gathering upgrades usually results in more than any other civs can deal with. With this boom, Shang also has the option to use all that food to launch a very strong tool attack.
My typical Shang start would go like this...
1) HC(CC)
2) Grab 2 vils BE quickly
3) Waypoint the 3rd vil quickly
4) Waypoint a builder quickly
5) House done waypoint him
6) HCC(C) and grab vil 4 as he pops out
7) AHA found berries and 2 vils are near them while the other two see some forest.
8) My two vils near the forest build the granary while the other two return to chop the strag(s) closest to them/TC
9) Vil 5 is born and joins the other 2 as foragers. No need to waste wood chopping time running that third vil past the TC before #5 is born.
Etc) New vils all go on wood until I need a 4th on berries and then a newborn becomes my 4th and final forager.
...once my pit is up I try to time it so 2 vils(builders) arrive at the coast to dock at the moment I have my 100 extra wood... while pumping FB, making the necessary houses and 3 or 4 docks all newborns go on wood. I may add a second wood pit later. I may send my 2 builders to the enemy to make trouble and they will likely be my house builders too, perhaps with some radar housing effect. I pump vils until I can tool and if I feel late I can stop vils or put a couple more on the berries since my berries last a long time with only 3 then 4 foragers.
Shang absolutely, kicks butt when this start is executed well and you can in general jam the granary right next to any berry patch and have 3 and likely 4 foragers working w/no walking which means that the other bushes are closer to the granary once the first ones are finished. Honestly, I won 29 3v3's in a row as Shang using this start and my first loss came in the AOEH tourney vs aloha when 1) I had poor fishing and thus was slower and had poor food intake once bronzed 2) They defended superbly vs my CA's w/their bowmen/slingers combo. 3) Are DaRq team communication was VERY poor and we gradually weakened and lost even though our Phoe did a decent job of holding off the enemy Shang early. I have lost a couple 3v3's since w/Shang but in general this start is really strong...neilkaz...
PS the key point with Shang is to lose NO time making vils.. Shang's only asset is a HUGE horde of cheap workers quickly produced, IMO.