in the morning of Sept. 1

[Itasan]

Do all these work?
1-1. Late IN the morning of Sept. 1, he went to an art exhibition.
1-2. Late ON the morning of Sept. 1, he went to an art exhibition.
2-1. IN the morning of Sept. 1, he went to an art exhibition.
2-2. ON the morning of Sept. 1, he went to an art exhibition.
Thank you.

[Tdol]

I don't go for 2-1.

[Itasan]

Thank you very much, tdol.
So 'at 8 IN the morning of Sept. 1' works too, right?
Itasan