Comment by ahuibers

Following Gladwell's 10000 hour rule, I would say you could probably call yourself a data science after 1000+ hours experience working with datasets successfully. As far as the math goes you should be able to do regression analysis, you don't need to know tons of stats but you do need to know stats and probability essentials (first few classes at a good school) deeply. I like this Wikipedia entry on "mathematical maturity": http://en.wikipedia.org/wiki/Mathematical_maturity; apart from writing proofs, it is very relevant.