Indexing

I’m new to Scrivener but established as a non fiction author. A bit late, but I’ve just actually read through the contract for my next book (just started but only 4 months left to write - a long story…) and it says that I have to provide the index. Obviously I can’t insert page numbers until the typesetting and pagination is done, so presumably I just need to supply an alphabetical list of keywords. Is this easy to do as I go along and how do I decide which words and phrases to index?
Thanks!

I don’t have much to offer, but I remembered seeing some other threads on the topic and looked them up for you…
viewtopic.php?f=4&t=31199&start=0
viewtopic.php?f=30&t=27875&start=0
viewtopic.php?f=30&t=24050&start=0

That last thread includes a link to this article which may also be of some use.