is it possible to not allow a workflow transition until a date specified by a custom field?

[Fidel Castro]

You can do it using "Boolean condition / validator with math, date-time or text-string terms" from JIRA Workflow Toolbox with the following boolean expression:

{00057} > {nnnnn}

replacing nnnnn with field code of your Date Picker custom field.

Note that {00057} is code for numeric value of Current date and time virtual field.

[Andrea Melde]

@Fidel Castro Armario

Will this plug-in update the assignee to a custom user picker field based on a post-function transition?

[Fidel Castro]

Yes, you can do it using "Copy a parsed text to a field" post-function with the following configuration:

• Target field: Assignee
• Parsing mode: basic

• Text to be parsed...:

  %{nnnnn}

replacing nnnnn with the field code of User Picker custom field.