Observation. If you like the summer rapidly fermented stuff, which tends to be creamy and thick with my culture, insulate the jar you are making it in during the winter. The microbes are generating some heat, and losing that to the air. You can limit the airflow quite a bit (I use a plastic top with some holes in it) and still lose the
CO2 from the fermentation but retain some heat. I also prefer the more uniform texture of the summer kefir, but some people like the more acidic longer fermented winter culture.
Honestly I just drink a ton of it and so I want it to brew up pretty fast.
One last thing about cultures, I am a fan of getting a local one. Almost always there is someone on craiglist selling for maybe $10, and that culture is ready to rock and likely to be more inoculated with local airborne cultures.
Took a month to get a good SCOBY for kombucha from a kit, and again, there is almost always someone who will
sell you one that is already active.
I've given away several cultures, and when I am travelling for a longer time I just eat the grains and restart from someone I have given one to when I am back!