To-do list(view)s with time displayed?

In a C# (3.5) Winforms app I have a FlowLayoutPanel containing a number of listviews. Each listview represents a short to-do list sorted in a sequential order with assigned priorities.

Occasionally a user has to create a new priority 1 to-do item.

An issue arises when there are multiple priority 1 instances - how does the user know which was requested first? Due to space constraints it isn't possible to show a date开发者_运维技巧-time field.

The listviews currently look like this:

Could I use some sort of watermark that shows the time floating on-top of the listview whenever a priority 1 is added?

A visual of what I'm thinking:

You could sort the the list by priority in ascending order, then by created date in ascending order. The tasks would then be listed from oldest to newest within each priority level, allowing the user to easily determine which task was created first.