Some would say the pinch isn't official until the whipsaws stop. Look at an example chart. Here's OCLR, i posted here on 5/16, can you see the pop from 2.11 on the 14th up to 2.62 on the 22nd? It whipsawed twice before hitting the 3.10 high. Some would say the pinch started on 5/14 at 2.11 bottom and some would say it didn't start until the higher low was formed at 2.28. Regardless of which camp you fall in, this is a typical and reliable pincher set up, and there is profit to be made from either entry, as long as you understand that whipsaws happen and how to play them.
There are 100's of great pincher charts posted on this board, if you look through some historical posts, I think you'll find that most behave like this with a whipsaw or two and the reliability is pretty high.