Custom field automation

I have a date picker custom field called "Financial Year". customFieldId=10035

I am trying to make an automated email notification when the date, picked up in this field is closing. Similar to my previous question https://community.atlassian.com/t5/Marketplace-Apps-Integrations/How-to-create-email-notification-when-Epic-deadline-is-close-to/qaq-p/1344247

However, I do not understand, how to insert a custom field in the "When" rule.

{customField} >= now() and {customField} <= 60d 

Thank you in advance!