How long do you typically think in the opening?

As for me I move quite fast in the opening phase.

I've devoted so much time to opening study that I can usually whip out 10+ moves of theory, if the opponent obliges.

Sometimes I even have a middlegame plan ready (oh the wasted time spent on openings--but hell, I enjoy it anyway).

If it's an opening I'm familiar with I'll usually just move automatically until my opponent deviates from the theory I've read.  If I don't know much about the opening I'll generally consider every move very carefully.

Depends...if its something i know and i play, then ill go through the first 10+ moves in 5 minutes.  If my opponents throws something new at me, then ill take longer.  But generally i like to be "out of the opening" using no more than 30 minutes.