As Raju mentioned, the only important piece of paper in P4 is the appointment letter - you will need that for medical exam and to enter the consulate. I got it in 3 weeks. It is generally mailed to you but in my case, for some strange reason, it was sent to my lawyer. So I would say keep that in mind. In case you do not get it before you leave, you can ask someone to pick up a duplicate from the consulate OR do it yourself once you get there (assuming you are from Mumbai).
A blank DS230 Part 2 is included but you can get it on the web. I did the same thing and had it ready. You have to sign it in front of the officer so you only need to have it filled. The instructions are now posted on Consulate website and they seem to be similar to the sheets included in P4. Documents mentioned in the checklist will be collected in the consulate - these are the "must have" documents. Other documents can be asked for and it is a good idea to carry as many as you can. In case you do not have it, your case will simply be kept pending subject to submission of that particular document. If your case is clear, Mumbai consulate is pretty cool.
If you have not scheduled medicals yet, I would do that first. Good Luck.
