Kefir – How to Properly Freeze Kefir Grains

The kefir grains are a culture of bacteria and yeast that are active at near-room temperatures. Their ideal temperature is 71F (22C). Below this and they will grow too slowly. Above this temperature, up to 86F, for extensive periods the grains will be damaged.

http://users.chariot.net.au/~dna/kefir-faq.html#temperature

Building the grains takes time- there's no way around it.

You can keep the grains at exactly 71F to maximize their growth. You can also change the milk often and keep the milk to grain ratio high to ensure that the milk doesn't acidify too quickly and the grains stay active.

You may see an improvement using organic milk as it won't have residual antibiotics in it.

http://users.chariot.net.au/~dna/kefir-faq.html#growthrate

I have not read anywhere of a way to modify the milk itself to encourage growth. You might experiment with adding a small amount of milk powder to make the milk more nutritionally dense but my gut feeling is that this would have a negligible effect if any.

I'm afraid your friends are just going to have to wait patiently.

From this comment on a passionate homemaking article, the commenter suggests that 2 Tbsp per quart of milk is an appropriate amount of kefir grains. In my personal experience, I've found that the amount is fairly variable, and that half to twice that suggested amount will produce kefir relatively quickly (how quickly, of course, changes with the amount present).

As far as separating them goes, they should pull apart relatively easily with the use of a couple of plastic spoons. While it is possible to smash them apart, this won't actually damage their ability to ferment kefir. My recommendation is to keep a 2 Tbsp measuring cup sanitized the next time you change out your milk, and add them to the fresh milk once there are enough to fill up the cup. The remainder can be used on another batch, eaten, or put in a sealed jar in the fridge with a smaller amount of milk to serve as a backup for later. Your worst-case here is that you just throw away the excess, which I would only consider "bad" if you can't find someone to give them to.