Victor Mair, noted sinologist and professor of Chinese at the University of Pennsylvania writes:

If I were the czar or god of Chinese and Japanese language pedagogy, I would not teach students a single Chinese character until they were relatively fluent — about two years.  I’ve always said that we should learn languages the way babies do; they learn to speak long before they learn to write.

and:

If you delay introducing the characters, students’ mastery of pronunciation, grammar, vocabulary, syntax, and so forth, are all faster and more secure.  Surprisingly, when later on they do start to study the characters (ideally in combination with large amounts of reading interesting texts with phonetic annotation), students acquire mastery of written Chinese much more quickly and painlessly than if writing is introduced at the same time as the spoken language.