Use Form 1040X as your secret weapon
You can file right now. But here's the sucky part: After the final instructions come out, you'll have to re-figure your taxes. Well, almost. And if any changes did occur, you will have to file a Form 1040X to amend your taxes.
There are 3 parts to tax instructions. Statute: the laws as passed by Congress, and published in United States Code (USC). Those laws don't micromanage: they give IRS latitude on the implementation. So IRS issues Regulations, the rules that implement the laws, which IRS writes as part of the Code of Federal Regulations (CFR). And the publications and instructions which the IRS publishes, for J Random Citizen to read. These "dumb down" the USC and CFR's excruciatingly technical and internally referential language, into something a citizen can easily follow.
Changes to both USC and CFR must be published, in the Government's fun little newsletter called the Federal Register. As a result, there is some lead time.
If you are a wizard, and keep yourself apprised of the statute and code changes, you can simply follow them The IRS instructions aren't alowed to contradict USC and CFR, only explain it. So you should be fine.