Best Time for Hosting Thought Leadership Events in Chicago and New York City: Morning vs. Afternoon Attendance

Hi - I am looking to do a thought leadership short event with clients and prospects in Chicago and New York City. I was curious to whether you'd seen better attendance rate when doing it in the morning (a breakfast 9-11.30am) or afternoon (4-6.30pm) - and if this changes for the each of the cities. Thanks for your feedback!