No. Tax year 2018 does not end until after 12/31/2018. A tax return cannot be filed until January 2019. The IRS has not yet even published when they will be accepting any type of 2018 tax return. Estimate it will be in late January or early February.
With the changes to the tax code and the tax forms it will especially be unwise to try to file early unless you want to wait for weeks to find out that your tax return has either been accepted or rejected by the IRS.
No. First, the software programs are still being updated even as the IRS has yet to complete issuing all the final changes in forms and instructions. Many IRS forms still bear the marking of for "Draft Only." Any attempt now will likely result in erroneous results.
Secondly, the IRS has stated that at best, they will not accept tax filings until January 21, 2019, at the earliest. Attempting to file now will not speed a refund and more than likely will contain errors as the IRS finalizes forms and computations.
Lastly, tax information forms sent to you reporting,in final correct form such as 1099-INT bank interest (which may likely include interest paid near the end of the year) and W-2 wages -cthese forms will not be finalized and sent to you, or be available to download in electronic form, until early January at best.
In addition to what DoninGA and Scruffy_Curmudgeon said, you cannot file your tax return until you have all your W-2s, 1099s, and other tax documents. Many of these are not sent to you until the end of January or early February. Don't try to guess what will be on them. If you guess wrong, which is very common, and the numbers on the tax return that you filed don't match the actual forms, you will have a problem. Wait until you get the forms.