The kitties are two days shy of turning four weeks (can you believe it?!). From what I've read, they should start getting aquainted with the litterbox around 5 weeks. Unfortunately, most sites won't tell you how to do this. Where's the best spot for a litter pan? How big should it be? What kind of litter material should I use? I've heard they pretty much train themselves, so will I need to play much of an active part, or just let them figure it out?