I have supercropped a couple of crops and I have found that I get the best results when I lay them down after 1st week of flowering. I usually SC the stalk just below the bottom most bud site. I will pinch the stalk between my fingers until I feel most of the outer stalk collapse... first you pinch the stalk on the left and right sides... then you pinch the stalk on the front and back sides at the same spot and then gently bend the stalk over to your desired location. I use supercropping to make my grow area into a sog.
As far as how much you bend them... I bend mine about 120 degrees... At first it looks like you f*cked up your plants... but rest assured after a few days they should start to support their own weight and won't look so broken... after about a week they will have mostly healed and will start to stand back up again... and about 1-2 weeks before harvest you should have a supercropped branches that are crooked about 35-45 degrees. They will mostly right themselves... but here is the thing.. you have to actually "snap" the branch a little.... it you don't the branch will continue to grow in length and not pop new flower sights. I find that I get about 30% more budding sites by super cropping and I get way better coverage.
To effectively supercrop you must exceed a 90 degree "bend"..
For best results use fimming instead of topping.... then supercrop the top
You should get 3-4 top colas if you do it right... with some practice you will find the proper location to fim then supercrop the top colas instead of topping them.
I have found supercropping far superior to sog or scrog or LST because you leave the plant to grow vertically at full speed, then supercrop, which makes the plant change over to stalk strengthening (to hold more buds) for about 3-4 days, then to making new flowering sights.
Best of luck... and thank God for his most wonderful creation...