there are about 50 questions---ANSWERED--- in this forum over the last week. just look for those
2018 is able to be Efiled as of over a week ago.
You need to REFRESH updates, at the bottom of the drop down menu under Updates...a regular update does not work.
Tax extenders still are not computing, so if the return has these, you may want to wait until those are ready.
I suppose that's the reason that option is there... for special circumstances.