Yes, the POF is required as part of your KYC to commence the intake process.  On the other hand, you could show POF from your existing account and still move the funds after that, as long as you inform the trading team.  The sooner the better, so as to get the intake process started.  Sometimes transfers of that size from one bank to another can take longer than we expected.  Perhaps you could show the existing POF, include a note in your KYC that you intend to move the funds to XYZ bank, and offer to produce a new POF after the money has been moved.