Understand that the date the property is converted to a rental (can be the date purchased) and the date the property is available for rent can be (and sometimes are) two different dates. Your allowed rental expenses that you can deduct, along with depreciation starts on the date the property is available for rent. For property improvements, the available date just doesn't come into play.
One thing I've seen others do with no problems is to include a "reasonable" amount of the cost of utilities (mainly electricity) in the cost of a property improvement. It takes power to run saws, floor sanders, cement mixers and the such.
