Yes, Jasper, I'd say you've gotten quite enough compliments by now, yes?

As for how long it takes, it really depends on the person. Noone learns how to do different things in the exact same time. If you went to school then you probably remember the kids who instantly understood something and the kids who didn't understand it after it was explained the umpteenth time. Languages are the same way. Some people just absorb all the rules and vocabulary quickly and with others it's like talking to a brick wall. In addition to that it's much easier to learn a foreign language if you've already learned one before. It took me 4 years to get where I'm at in Russian, but now I've been learning Arabic for about a month and I can speak Arabic now as well as I could after learning Russian about a year.

Besides that you haven't told us what proficiency level you're aiming at with "know Russian." You could say some person who learns maybe 10 words in Russian knows some Russian. Someone who can speak fairly well but can't read at all knows Russian. Beginner, intermediate, and advanced students know Russian, and they all took different times to get to where they're at. If you mean how long will it take you to get all the main grammar rules down and have a decent working vocabulary, then anywhere from 2-4 years(if you're an average language learner) if you have a class and maybe a year longer if you're learning by yourself. It is quite possible to learn all the grammar rules of Russian and a similar sized vocabulary in only a couple months. That is, if you drill every day. But most "casual self-taught language learners" I've run into are the kind that might pop a tape into their car once a week or something and forget about it. Not to say you're like that, of course, but what I mean is not everyone is really serious about learning languages.