When your purchase of a building is on zero hits and says old why don’t I get my flowers?

You're misreading it as Old while it actually says 01d which means you still have one more day to go before you get flowers.

Unfortunately the font is tricking you. When you see a timer that says "old" it is actually means 01 d "zero one day" which equals 24 hours. So if it shows "01d 00hr" that actually is 24 hours that you must wait.