When do I need to send you the text?
The index cannot be compiled before the text is complete (including location of illustrations, tables, figures and diagrams).
Unless the index is to be embedded, the text needs to be in page proof format (ie typeset into the layout that will be published) so that the page numbers recorded during the indexing process will be the actual pages where the indexed text will be found in the final publication.
I therefore need to have the proofs towards the end of the production process but allowing me time to produce an appropriate index. For an average book this will be around 2 weeks before the index needs to be typeset.
An embedded index in Word can be produced after the content is finalised, before the proofs are produced. It can be supplied in stages, in chapters for example, providing these are completed. The index entries are 'embedded' (i.e. 'hidden') in the text itself and Word will generate the page numbers. If text positions are changed therefore, this does not affect the indexing as the index can be generated afresh after the changes.