Just a word of caution.. firstly.. as has been stated, text books are a guide, they do NOT tell you HOW to dance, but, what you you should base your foundation work upon.
I have seen on another site, quite recenly,a topic about the distinction between Q and S rhythm in F/T.
There are Many advocates saying there is essentially no difference.
Where do these " theories " emanate from ?... watching the interpretation of world class exponents .
The inherent danger, is that many may confuse the basic foundation, with these more advanced ideas, and remember, these are PERSONAL interpretations, and should be approached with some scepticism .
To your Q... I have to defer to the current techn.still being used by most as 3/8 over the turn including Guys book.. and of course, amounts may be varied depending on the following figure ( Rev. wave for e.g. )
All of the " new " editions in the ballroom technique, are not yet cast in stone , and each Soc. will adhere to its current format, until a general consensus deems otherwise ( If ever ! ) .
I hasten to add, that some of the newer theories have merit , but the jury in the " establishment " , is still out .