Nothing is deductible until the house is actually available for rent. Up until then, any improvements are just added to your cost basis. If you only own one other home, mortgage interest and property tax is deductible on your personal Schedule A.
Once the property is available for rent, meaning advertised and ready for move in, you can then deduct rental expenses against the rental income. One of those expenses will be depreciation, which is based on your cost in the property at that time when it becomes ready for move in.
