That is my question!! I have read so many different things about this and they all somewhat conflict. I am growing Purple Cherokees, early girls, yellow pears and sweet 100's. I have to admit that I did pinch a couple of the seedlings to make them "bushier", but they seem to be the leggy-est of all. I now know that I did this WAY too early, too! I didnt do all of them, thank god!
I am wondering, though should I do it in the future?

Instead of pinching the plants back, plant them deeper in the containers. Tomatoes will develop roots on the stems if they are planted deeper. This will give them a better root system before you plant them outside.

Alot of the info is misleading. I cannot speak for you growing in Ca. It really depends on what you want to do and where you grow. If you have alot of sun, and have leggy plants, the tomatoes will suffer from sun scald. Bushy plants shade the tomatoes. I leave mine alone and see what each plant does. I pinch when I think it needs it. Most of the time I don't. My best results come when I cage them and let them grow! Pepper is right also, I plant mine deep to develop a good root system. For tomatoes that is always a must.

Though this is just hindsight - I always plant my tomatoes just 5 weeks early, to prevent this - 6-8 weeks reccomended traditionally is WAY to long, in my opinion, as all of my tomatoes end up leggy, and planting the smaller, upright ones seems to produce earlier tomatoes. May 8 is the last frost date here, and I always plant on April 1, or first weekend after. I have found the same with the peppers - the 8-10 weeks reccomended by most causes about half of my seedlings to flower by the time they are out, so I plant them on the same day, and they go out after 6-7 weeks.
Something to consider for next year.

Dave

Are you growing determinent or indeterminent tomatoes?
"Pinching" determinent, which grow just so far and then produce all at once, may make a bushier and slightly more productive plant.
"Pinching" an indeterminent is not going to do much of anything except slow production down since the start to produce fruit when they reach a certain stage of growth and keep on producing until something kills them.
Very often one of the real hazards of offering advice is knowing what the real question is, or when reading that advice knowing just what th person offering that advice is really talking about.

I pinch the suckers that grow out where a good sized branch comes out until the plants are 3 feet tall, then they are on their own.
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BUMP