I purchased an investment condo in early Dec. 2017 that required work. It will be available to rent in mid-Jan. 2018. Can I deduct any of the expenses in 2017 or 2018?

The work to get the rental property ready to rent will be added to the "Basis" (similar to cost).

That will start in 2018, when it is available for rent.

Thank you! So for 2017, would I leave the rental property off of the return completely?

Yes.