Trump could wait until January before signing the tax reform :

While a final text of the tax reform was passed yesterday, President Trump may not sign the law immediately.

A postponement of the signature would probably not be negative for the markets. From the moment this is done in the coming days, the timing is not so important.

If Trump waits more than 10 days, the reform will automatically be adopted.

The main reason for postponement will be the fact that Congress first needs to vote on a resolution to continue funding the government, while the current provisions end on Friday.

Congress must first vote on government funding. If this is not the case, Trump will have to sign the reform in January.