The waiting part is up to you and when you want the new build , it's always nice to see what the next best thing will be and sometimes it's a bust so that's the chnce you take. The waiting also will let you see what Hswell is and if you buy now and Haswell if a great cpu then you would kick yourself for not waiting. So wait for Haswell and then you'll have three choices , maybe.
The decision between the 3570k and 3770k depends on what your main purpose of the computer is. If the main use is gaming then thee won't be much of a benefit in going with an i7 over an i5 , the 3570k will give you the same performance that you would get fro the 3770k because in gaming the part that makes the biggest difference is the vieo card.