What date do I use for when I started my business?

[bnclined]

I wrote a book over the last decade. In 2015, I paid someone to edit it. In 2016, after working throughout the year to prepare it for publishing, I finally self-published toward the end of the year. I've been told I can take the editing expense in 2016 as "start up expenses". But what date should I use for when I started the business? I worked on preparing it for publishing all during 2016, so 1/1/16? or when i actually published it?

[DDollar]

If you worked on it all of 2016, I would use 1/1/2016 as the date you started your business.  And yes, you can deduct what you paid for editing as start up costs.