Yes, as somebody already suggested you should first read your contract and see what it says. It is so different between the contracts and landlords. But if you accept appartment and then you say no before signing the contract, sometime they charge you 100-200 CHF.
If you are not coming before January but think it´s something interesting for you, ask them to mail the contract to you.
And for your question: what if I find better appartment? Well, it is a decision as every other we have to make.