There is no reason to wait to file other than the IRS will not be accepting any 2020 tax returns until February 12, 2020.
Whether or not the House passes any legislation, it has go to the Senate where changes will be made, then it goes back to a House/Senate committee to iron out any differences. If that is finally approved by both the House and the Senate, it has to be signed into law by the President if he agrees with the legislation. He could veto the legislation and the process starts all over again.
When finally signed into law, the Treasury Department and the IRS have to write new rules and regulations based on the legislation. This usually takes a few months to finalize. Then the IRS issues guidance on how to claim any new credit, IF and ONLY IF, the credit is based on a 2020 or prior tax return. The credit could very well be for tax year 2021.