I am very new to this myself. I was very worried that if I didn't make the kits exact to the directions that I would screw it all up. I was also very upset that it wouldn't turn out exactly as it is supposed to if I made any mistakes (which I did). Given some time and reflection I realized maybe I don't want a kit to taste as intended. I want it to taste how I like it, and we can adjust them to our tastes.
I just bottled my first kit. It was an 8 week WinExpert Shiraz, and I gave it an additional 3 months after the bottle date. It is very nice, better than our regular store bought 'go to'.
Many here bulk age (in carboy) from 6 months to 3+ years. The best advice I have gotten to date is wine is ready when it tastes good. Time is the first variable, but also your taste, and possibly making adjustments for it. Adding acid, etc.
It's ready when it's ready. If you like it, bottle it. If not, give it more time. If it's not coming together, ask questions, maybe it needs a little tweak to make it more to your preferences.
I did a taste test on 2 kits the other day and both are at 3 months past the bottle date. They were not very good a month ago, but by MY tastes they are ready to bottle. I find a kit wine seems to really start to come together with an additional 3 months beyond the 4,6,8 week kit time. 3 of the 4 that have reasched this date are all pleasant. The Pinot Grigio is not as tart as I prefer and I just added a little acid to see if that will liven it up.
As I am new, I am splitting my 6 gallon kits to a 3 gallon carboy and bottling half. Who wants to wait a year to taste their first batch? This way I can enjoy what is to me a very drinkable wine, and give the rest more time so I can get an understanding of what it can be. I also took 4 bottles and put them away with 3,6,9 months and 1 year dates on them so I can gauge the development and decide where time and flavour development merge into a sweet spot for my taste preferences.
Welcome to the WMT.. Have fun!