Ouch! My Zinnias are about 4" tall and 3" wide and we have transplanted them into their own pots just yesterday. I didn�t know that you were supposed to pinch them! Thanks for the post! I do want to know where and how you pinch them.
You can see my plants on my blog. Just scroll down to Growing from Seeds Update.

Here is a link that might be useful: Growing from Seeds Update

I pinch my zinnias between the 4-8th set of leaves.

No real wrong or right answer, they will just bush out more, not black and white on which exact pair of leaves to start pinching.

Keriann~

Thanks Keriann!

Jerry, when you pinch the leaves you will get two new branches. If you pinch the new branches again at some point you will then have 4, etc... You will get a more bushy plant rather than a tall slender one.