If a bank received a mortgage loan application prior to Jan 30th, and the customer subsequently changes the product, i.e. fixed to ARM or ARM to fixed, does the bank need to provide the new disclosures on the new TILs (eff Jan 30th), or should they provide the new disclosures on the old forms?

You can do either.
Myself, I've elected to keep old with old all the way through the closing. But that's just my preference in keeping with the K.I.S.S. theory.