...what's the fastest you can make wine from fresh fruit?...
Look at the commercial wine industry.
Each year, the first Beaujolais comes out in the middle of November. (Third Thursday to be precise.)
Variations in the dates of both the harvest and that third Thursday mean that the time between harvest and the first consumption varies between 6 and 8 weeks.
Is it any good? I'll put it like this: when I lived in Europe, I used to look forward to it as a once a year treat but that was all and my wife made it clear that she put up with it as a once a year burden.
Sometimes, wine can be made even faster. In 2003, Europe had record breaking high summer temperatures. At the start of October, I noticed that my local supermarket was selling a French Vin de Pays en Primeur. Even though the harvest would have been earlier in the hot summer, this surely meant that the wine was in the shops not much more than 4 weeks after harvest. I bought a bottle and took it home. My wife rolled her eyes in horror and I opened it and poured it out. Wow! Full bodied, plenty of tannin, rich and very satisfying. Undisclosed grape variety but clearly mostly Cab Sav.
So, the answer is that it can be as little as weeks and not months but you really need to get the right fruit in order to get away with it.