welcome dreamscometrue

nice name , and in my experience they do come true , but you have to work damm hard to get it to happen lol
your ladys in kharkiv ??
great city , my wife is from there also ,
so ??? ill assume afew things ,
first you have been there yourself , you have done the fiancee visa application subclass 300 ?
did you use an agent ? or did you do the work yourself ?
when did you get notification the application had been recieved by IMMI in australia ?
when & who is your case officer in the australian embassy in moscow ?
as all applications normaly are handled through that office
She had her interview in September and is due for her medical in Kiev mid October.
how long was the interview ? where their two interviewers ?
did she have it in kiev personaly or was it via the phone ?
have you found an approved medical clinic in kiev yet and made the booking ?organised train tickets /bus etc
from memory it was about $200 australian for the medical for my wife and child
NOW WORD OF CAUTION WITH HER MEDICAL
make sure she understands to not go to the MEDICAL IF SHE HAS ANY SIGNS OF A HEAD COLD OR FLUE !!!
it has happened that some emdical centres to generate extra business dollars , will requier a lady with a simple head cold or flue who has tested negative with blood & xrays for TB to still return a week or so later to do sputum tests over several days for TB
this pays them extra dollars,
now generally the clinic doctors will know the persons dont have TB, but they can use different incubating /path test methods to get a final result , one such method can hold your medicla report up for as long as 12 weeks , before it is sent to IMMI at the embassy for processing with your file
your fiancee , should already know if she has TB , likely she doesnt , & under the code of practice at medicals conducted for australians mandated by IMMI the clinic must notify a person if they find any serious illness etc
SO she must go to her medical with no flue or cold symptoms at all , or it could add possibly 3 months to your wait , i know of two couples this has happened to in recent years , both had no sign in blood or xray of TB, but clinic ran extra tests anyway , held up their applications

how long it was from the interview and medical did it take on average for the visa to be approved.
NOW finally , to answer your main question,
there is no set time for approvals , it will all depend on how good your application for the sub class 300 fiancee visa is !!
how long you have known her , etc etc
can they easily see a genuine loving relationship has been established ?
however having said all that if your application was solid and good , you could reasonably expect a visa may be granted about 1-3 months after all docs have been recieved by your case officer in moscow & interviews /medical are all completed etc
have you checked with the case officer they have all required docs ?
hope this helps , fell free to ask more
SX
EDIT , POSSIBLY THE MODS CAN MOVE THIS TO THE VISA IMMIGRATION section ??