AHHHHHHHHHHHHHHHHHHHHH, sory I just spent the last hour responding to this and closed the wrong browser tab and lost everything I wrote, ARHG. anyway I will resurrect some of the main points
In reguards to the main point of the thread, when to get FFS. I actually had the same question, and IMO it might be advisable just to get a professional opinion from a FFS sergion or someone who knows a lot on the effects of HRT. And if you're concerned with passabillity, just play around with photoshop or a similar program. You'll probably find, as I did, that hair and eyebrows can make all the difference in looking male or female.
In responce to who said there are no male or female faces, sorry but thats just ignorant. Take a look around, I asure you'll notice that the majority of men have the predominant brow, less rounded forehead, and more square jaw. there are definite differences. Granted there are those who arent "typical", Sigourney Weaver and Leonardo DiCaprio, are just a couple of examples. and then keep in mind race plays a factor too. Asians have a more neutral facial structure, while euro-caucasians have more distinct differences in facial structure between sexes.
Unfortunatally, Social expectations do play a huge part in an individuals comfort in life. If you look like a "typical" female, In our society it will be much easier for you to live a comfortable life as a TS woman, I dont necesarilly agree with it, but its a fact of life these days.
To put it simply (as others have already said) do it for you, if you're happy without FFS then dont get FFS, if it will make you happier or more comfortable to get FFS, then do it. Everyone has different reasons for doing what they do, so if you want to do it, do it, reguardless of others opinions about why your doing it.