I'm picking up the boutinere on Satuday afternoon, she's dropping off the bouquets on Sunday (wedding day) at 10am, and the ceremony doesn't start until 4pm. SO, you could definitely pick them up in the morning and they'd be fine in the afternoon.
I would ask the florist- For my friends wedding they dropped them off at 8am when it was a 6pm ceremony... They were all in vases and she kept them downstairs where it was cool. They did pretty well overall. I would have had them dropped off later though if was a choice