I have found it is worthwhile to do some calculations of taxes before the end of the year to identify profitable last minute adjustments
This can be done with the previous years software by copying a return and then modifying key entries to see what differences they make.
If the laws have not changed much, this should work.
However, a new copy may have any changes (of course, if the Trump changes go through there will be major changes). Also some things can be entered once, especially if they are not likely to change, saving you time when you finally do your taxes.
The issue then becomes what to buy, and when.
In last two years I went with Taxcut (H R Block) because of their Amazon offers, but this year it is only 5%. Since I can get that with my Amazon store card, and several credit cards, this feature is no longer important to me. .
Historically, there have been offers from financial firms for discounted versions, or even free versions, if you were customers or had certain amounts with them. Are any of these announced now?
It may be false economy to wait for one to save a few dollars on the software, and lose thousands on taxes, or hours of extra work.
In the now expired offer on Amazon discussion, it was pointed out that by getting the downloaded version of Amazon you could use credits you had from accepting delayed delivery of Amazon prime items.
It seems that on Amazon now, the HR Block is significantly cheaper for comparable products. For instance the Federal only download is $17.20 ($39.99 with state)
Turbotax Deluex Fed seems to be $39.86 for disc and more if downloaded.
I suspect if the Tax laws get rewritten, no early version will be accurate, although you may be able to make them work with overrides, etc.
Having used both, I recall Turbo as a little easier partially because I have not figured out how to keep two forms open with Taxcut.