I jumped right into Java and Android at the same time knowing basically nothing about either. I had about 2 years experience with C doing homebrew for nintendo DS so nothing was really OOP and it was all single threaded.
Since you know what you do of Java, I'd say you'll be fine. The bottom line, is that slow is good. Take it easy, take it slow and don't skip ANYTHING. The provided developers guide is very solid, covers all of the important concepts. An early piece of advice... don't block the UI thread... If you're going to write a game pay special attention to how to create a proper game loop thread. There's really not a lot on that provided by Google (except for SDK example games) but there's information out there.
