Does this also apply for a period when improving a home for rent
No. Expenses incurred in preparing the property for rent for the *very* *first* *time* are not deductible. DO NOT confuse this with property improvements.
Basically, repair and maintenance expenses incurred "before" the property is placed in service are just flat out not deductible. That would be things like utility bills, lawn care, fixing the broken garage door because it won't open, etc.
The property is in service on the first day a renter "could" have moved in. That is also the same day the "days rented" count starts. This is usually the day you put the FOR RENT sign in the front yard. If on that day a potential renter walked up to you with the deposit and first months rent physically in their hand, gave it to you and you accepted it and they could starting moving in at that very minute, then the property is "in service" on that date.
