Does anybody know of a way to use absolute timestamps instead of relative timestamps in a timer list?

For example:

pressing C-c C-x - starts a list with a relative timestamp like so:

- 0:00:00 :: First item

Pressing M-<RET> adds more items to the list with the corresponding relative timestamp like so:

- 0:00:00 :: First item

- 0:00:05 :: Second item

- 0:00:12 :: Third item

I think this really cool but i'm also looking to have the option to use absolute timestamps like so:

Not sure if this has been raised before. I did have look around but didn't find anything. Any pointers would be great!

Regards,

Rob