We began renting a property in Oct 2018. Can we deduct expenses that we incurred to get the property ready to rent? (While we were still living there?)

No. The property has to be available for rent in order for you to start deducting expenses. You don't have to have rental income, it just has to be available for rent.  That's means, for example, that you've started advertising it for rent, or listed it with an agent as a property for rent.