Split text in Google Sheets with a delimiter which contains spaces

I have a column (A) in Google Sheets where each row contains the following string:

"TEXT on MORE_TEXT" or, for more specific example "occurred on December 17, 2020". The "MORE_TEXT" part can be any of the 12 months.

I need to split it so that the "December 17, 2020" is in a separate column and my desired delimiter is " on ", which is a space character followed by the word "on" and then another space.

But when I use =SPLIT(A:A," on ") it ignores the spaces around "on" and I have no other ideas.

I am sure I am about to learn something simple but effective and am looking forward to it.