Contractors typically are used to getting 10% down at the signing of their contract, and another 30% when materials are landed at the sight. That hasn't been the case with a Standard 203k where they must work soley on their own credit and cash to get started then get "reimbursed" for each phase to get their money back.
The "Limited 203k" loans, per the guiedline always provided 50% of the project cost for materials  up front to the contractor unless you were dealing with a lender like Wells Fargo that only allowed 35% or Prospect Mortgage at 40%. Most other lenders still provide the full 50% per the guideline. Years ago I would see B of A, close the loan and in many cases it took them up to six weeks to provide the "50% up front money". These "limited 203k" project were quite often only going to take 30 days to six weeks to complete. They finally got with the program (years ago) and started providing the money from escrow at closing.

The new rule as it is proposed for

Standard 203(k) transactions, Mortgagees may disburse the following at closing:

• permit fees (the permit must be obtained before work commences [to be reimbursed at closing]);
• prepaid architectural or engineering fees;
• prepaid Consultant fees; [reimbursed to the borrower] [This can be added to your escrow instructions to be used as part of their down payment or closing costs too]
• materials costs for items, prepaid by the Borrower in cash or by the contractor, where a contract is established with the supplier and an order is placed with the manufacturer for delivery at a later date; and
• up to 50 percent of materials costs for items, not yet paid for by the borrower or contractor, where a contract is established with the supplier and an order is placed with the manufacturer for delivery at a later date
• For any Disbursements paid to the contractor, the Mortgagee must hold back 10 percent of the draw request in the Contingency Reserve.