There are lots of ways to set up to tie the Bimini. Some people loop it around their toe, others find a hook and still others prefer the reel handle. I don't think it really matters what you use to anchor the loop, but what is more important is that you find a comfortable way to do it and make sure that you will be able to tie it the same way on a rocking boat in the middle of the ocean. The Bimini is a knot that you really need to know how to tie with your eyes closed.
The purpose of the knot is to double the line without losing any strength in the line. When you tie a knot with 2 strands versus a single strand it will be twice as strong.