Thing is, if you've got a sense of rhythm give it a couple of hours and you'll be able to at least beat match. Give it another couple of hours and you'll be getting basic mixes off ok
I think this is being really very optimistic, unless the person is an amazing natural.
It took me a good few weeks of practice before i could really be happy with any mix i did.
A year later, I was confindent enough to play live, due to practicing most days for an hour at least.
I think this is a fairly average timeframe for learning to DJ at the lowest level. Add on top of that the addition of effects units, third decks, etc. and I think it's fair to say that a top class DJ needs to have done as much work to get where they are as many musicians.
Anyway, that's just what I think....and it's a bit off topic. Sorry. I get a little annoyed when people seem not to realise what's involved.