If you bought it from your LFS - it may already be aquarium ready.... i.e. will sink! However, sometimes it doesn't! Which is kind of a pain! Also it may turn your water brown for a time - no problems there, just a bit unsightly. Which is why it is recommend to soak it. However, I don't thikn 3 months is necessary. Sometimes boiling also helps to get the tannins (brown) out of the water a little quicker.
Check and see if it sinks or floats and we can go from there! There are some tricks to keeping it underwater if you don't want to wait. Good luck!