It is a good idea to start young. If you can speak German then speak often to the child in both languages. Tell them how to say things they ask for in both languages. Repetition is the best way.
Play music at night while your child sleeps that is in German and in English. There are many videos that you can let your toddler watch that also teaches the language.
At this age Children are like a sponge and will learn a lot. Start out by teaching them simple words. Keep practicing them every day. Once they get those words you can teach them more words.
Yes, if you keep things simple. Just start with a good set of flash cards to build vocabulary. You also need to have conversations in German in front of your toddler daily.
