Definitely not too late. Is it too late to start teaching Spanish?

course not!
HUGE fans of Signing Time here! Signing Time even has its own signing classes now, Signing Time Academy. Check
www.signingtimeacademy.com to see if there's an instructor near you. The classes are super fun and PERFECT for a 2 year old. The DVDs might be at your library too, so check! My dd is 3, started signing at a year, and still signs daily. (And her speech is fine, its just a fun language and she likes it) She loves teaching signs to her baby brother, and will spontaneously be like, (saying/signing) "grass!" if we're outside sitting in the grass. Its pretty stinkin cute.
Anyway.. as for tips starting.. Signing Time dvds will probably have pretty darn quick results. (Had my 12 month old signing "dog" after just a couple views) but you can choose a handful of signs to work on yourself, no tv required. Definitely include signs that are things s/he finds interesting. Not just things like, milk, eat, potty/diaper, more, please, thank you, hurt..etc. Those are very USEFUL signs, but they are not INTERESTING signs. Kids want to tell you about things that excite them! They want to say "look at THAT, mom!" So definitely teach the "useful" signs but include an even mix of "fun" signs. Cat, dog, bird, ball, airplane, car, ice cream, hat, train, balloon, bubbles, flower.. if your lo finds it interesting, sign it! You can have a lot of fun with it at this age, and make up simple games. After you've demonstrated a few signs enough that you're reasonably sure s/he knows what it means (even if not signing back) get out a picture book and say, "can you find a DOG on this page?" (but sign dog instead of saying it)