dang nobody gonna say anything more? I figured you guys would be telling me all kinds of stuff.
When you are ready to ferment your juice you take a hydrometer reading. Depending upon how much alcohol you want in the end will determine where you will start. Too little alcohol and the wine won't last. Too high and you'll be able to run your car on it and you won't be able to taste the fruit in your wine.
My juices from Calif. are always at 1.092 this will give you 12% alcohol if the sugar is all eaten up by the yeasts. Your reds are usually started here. (personal pref. of course).
White can but don't have to be a bit lower. Fruits such as strawberry, cherry, cantaloupe etc. can start about 1.080 which will yield about 10% + in alcohol.
Keeping you wines above 10% should allow them to age awhile. Providing of course other factors such as temp, sulfites, tannin acid etc.
When your yeast is introduced into your juice it now becomes your "must". Yeast will feed upon the sugar and excrete CO2 and alcohol. As the sugar is eaten the hydrometer will fall further into your must. How fast depends upon many factors but in about a week it should be around 1.000 + or -
When the hydrometer has not moved for 2 to 3 days at or near his point your sugar is most likely all eaten up. Now you may rack your wine off of the sediment "gross lees" and clear.
Temperatures will cause your readings to be off, that is why your hydrometer is calculated at a base point. For a true reading you will want to adjust your readings.
Wine making isn't rocket science but being close is good enough for most of us IMO.
Hope this discertation helps and there will be a test on Monday. Study.