I'm pretty new to the concept of lucid dreaming...I mean calling it lucid dreaming, but I have been lucid dreaming since forever.. all my dreams are basically lucid dreams and I've been controlling what I do in my dreams since I was 5.. I do find it hard to control everything though when there is someone I love in my dream that I have to protect... anyway, I don't really know how to control the time either.. I have spent a couple of "days" in my dreams before but I forgot how I did that... really depends on what you're dreaming about too..the pace of it..
Sometimes, when I've wanted to stay longer in a dream, I just sent myself into a deeper sort of sleep.. I was more.. I guess conscious in my dream, then.
Like I said, I'm pretty new to the whole lucid dreaming as a real concept and all it's properties... but I do know what I've experienced and all the things I can do.. From what I've read so far, I think I can do basically anything..