disable the "Post" button in the Enter Journals form when the creator of the journal is the same as

We have a requirement to disable the "Post" button in the Enter Journals form when the creator of the journal is the same as the person posting it. We are able to achieve this partially through Form personalization,however, the post button gets enabled when an update is made to a journal and the user clicks the save button. The WHEN-NEW-ITEM-INSTANCE trigger is fired after the save button is clicked and it is very time consuming to create a personalization for every field using trigger WHEN-NEW-ITEM-INSTANCE. Please let me know if there is a workaround for this. Thanks.