As a fellow first time cat owner (my mother has had cats before, but it's my first time with feline friends), I would perhaps say that you should be more lenient about dirt coming into the house. Whilst it's not pleasant having outside mess come onto your house; kittens can make some mess and we have to hoover regularly. My two mainly make litter mess though (i.e. when they tread on their litter we often find it around the living room). My two are still house cats though when it gets warmer we're planning to let them outside, and they don't make an incredible amount of mess. If you live with other people though, I would ask them their opinions as I think that everyone needs to be on board with the cat so that it can have a fully loving home - not that I'm saying that you will mistreat it, but it's just something to consider Good luck with your little kitten though, I love Siberians!