'Advance online publication' for articles

We are looking for a way to correctly indicate 'early online / online first / ahead of print / in press / advance online publications' in article metadata.

Currently, we are putting 'Advance online publication' in the Start page box, and a full stop in the End page box, however this does not produce a correct reference when the citation style function is applied on lists (it adds a dash e.g. 'publication-' but this is the closest we can get at the moment). Putting it in the new Number field does not work either.

It would be great to have a solution for this.