I had this meeting in August and it went fine as I got my JA sorted. I found the inspector to be very business-like and fair.
Everything DSFA want is itemised on their letter, including how long back they want the bank accounts. What I did was go through each requirement in their letter (a,b,c, etc) and put all my paperwork into separate folders (marked a,b,c, etc) as it makes it a smoother procesess when you are in this meeting and you are being asked for lots of documents, you can then refer easier than wading through a pile of paperwork. This will take you a little while of effort but I found it worthwhile. The inspector will xerox a lot of the documents and give you back the originals.
I suggest you familiarise yourself with what the entries (particularly lodgements) are on your bank a/c statements so you have answers.
Good luck with it, it's worth it when you get the benefit sorted.