Re: when and how to teach your native language?
I would start to teach her now. Her brain is at the perfect age to act like a sponge and pick it up. Start to throw in Russian words when you are speaking English. Say do you want МОЛОКО? And then point to the milk jug. As she gets used to the Russian word for milk start to change the entire question to Russian. At that point she'll understand the word for milk and will begin to understand the first part of the sentence.
Also, look into a Russian program for preschoolers. That will be a great place for her to learn and have fun with other kids at the same time. If you are in a bigger town there will probably be one. Some friends of mine send their daughter (almost 5) to a German preschool. Her mom is German. They spend half the time in school speaking in German and the other half in English. When she is with her mom her mom only speaks German unless the daughter doesn't understand. Her dad usually speaks English, though he inderstands German. When the 3 are together they usually speak English. It works very well for the girl. She is very good with both languages.
Good luck, it's a great idea for her to learn now, then when she's older she'll be lucky enough to already know a second language and it will be very special that she can communicate with your family.
"Go slowly, breathe and smile" Thich Nhat Hanh