"all of today" here means "the whole day" or "the entire day" - the speaker does not have a free moment at all during the day. In another context you could say "all of" the world wants peace, ie the whole world wants peace. "as far as" is an idiomatic expression, which can mean "regarding" or "to the extent that". Literally, "far" is an adverb of distance, ie, "far away", but that literal meaning does not apply here, you have to take the whole expression "as far as" as meaning something different. "But as far as time goes" in this context would be "with regard to specific times (when I am free)" - it sounds as if the speaker is suggesting the possibility that a change to his/her work schedule could open an available time in the future. Your first example "as long as" means something else again: specifically it means "provided that" or "if". Once again, it is idiomatic. "Long" does not literally mean "long" (as in length). It is just an expression that only makes sense when you use all three words "as long as". As long as/provided that/if you work hard, you will succeed.

Hey Kai, how are you, buddy? Right before providing you with a proper answer, I should congratulate you upon posting such interesting questions on the italki board here! 1) ''As/so far as'': It is an idiom used to mean ''to the degree or extent that'' / ''as much as''. E.g.: ''They returned at nine, as far as we know.'' E.g.: ''I will help you so far as I am able.'' * Depending on the context, it may have another meaning, which is ''To the extent of...'', as in ''I wouldn't go as far as calling that a riot - it was just a bunch of kids causing troubles, you know!'' 2) ''As/so long as'': it is an idiom that means ''Provided that...'' or ''On condition that...'' (You might hear people using ''just so'' to convey the same meaning) Eg.: ''As long as you tidy your room first, you can go out to play.'' E.g.: ''I can lend you my car so long as you promise to take good care of it.'' E.g.: ''You may have another cookie just so you don't take the last one.'' * The expression ''As long as'' is sometimes used in the sense of ''For the period of time that...''. Though the correct construction should be ''For as long as...'', the usage of the preposition ''For'' right before ''as long as'' is sometimes omitted from the context: E.g.: ''We promised to be friends for as long as we (shall) live.'' E.g.: ''You may stay out as long as you like.'' E.g.: ''I told her to keep the book (for) as long as she wanted.'' "I’m busy all of today unfortunately, I work until very late tonight" = --> ''All of today'' means ''for the whole/entire day TODAY (''all of'' is an idiom that means ''the entirety of something''). "But as far as time goes my schedule changes" --> I should think that the expression ''As far as time goes'' means that ''as much as you work'' or ''as the time of work goes by'', your schedule is likely to change. Here, I dare believe the speaker is implying that any sort of change in their work schedule might open an available time in the future. Hope that helps!

Hi Kai. As an English learner, can I offer some ideas? "all of today" = the whole day today. He was busy thoughout the day, every part of the day today. "All OF" puts emphasis on the entirety of something. Compare these: all material - all of the material (each piece of the material) all week - all of the week (each and every day) all towns - all of the towns (each and every town) all books - all of the books , etc. The latter options imply "including each and every item/unit/period" etc. "As far as time goes" - My feeling is that it can well be replaced by "as long as time goes" and there won't be any big change in the meaning. The idea is , as I work (till the moment I have finished the work) my schedule changes, or, all the time (that) I work my schedule changes. As soon as I stop working, it stops changing (not for sure though). I'd say that "as far as" usually shows that something is true or valid to a limited degree. While "as long as" usually shows a condition, requirement or a reason and in its meaning is closer to "since". Check out the usage of "as long as" here, you can find some good examples here: https://www.ldoceonline.com/dictionary/as-so-long-as Hope I was able to help a little.