Exactly what Rookie said - it's all about watching. Rock bottom is what investor sentiment is. If investors are confident and there is a lot of pumping, more than likely people will put money in... it's a rebound. Hard to tell where rock bottom will be. It's all about watching the stock, the forums and the news like a hawk.
Best of luck my friend, truly. I tend to follow my gut and thats the best advice I can give.