It's hard to say, because so many factors go into a credit score and no two people's profiles are identical. For me, I went on an app spree last Aug and was approved for four new accounts. By the time all of the new accounts hit, my EQ went from 723 down to 695. But by the beginning of Nov, I was right back up to 723 again, which was a faster recovery than I expected. Why did this happen? I don't really know... ah, the mysteries of the FICO algorithm.
That being said, you should expect to see some recovery by six months, and all of the ding from the inqs should be gone by a year, even though they will remain on your reports for two years. The best thing that you can do is to use your new accounts responsibly -- always pay on time and keep your reported balances low -- and enjoy your new cards as you wait for your scores to bounce back..
It's also going to depend on your utilization on the cards. I know a lot of people here on the forums have suggested keeping a 1-9% balance on one card, and paying the other cards in full.