If you open a file and go to Help>About InDesign
But hold down SHIFT CTRL when you do this. (key combo could be different on Mac)
You can then see the documents history and you can even write a log file.
But it doesn't include the actual time spent, just the times it was saved....
I had a look through a document history before posting, on each date up to the last month I was able to give a round about figure on what was changed on each date.
Maybe it's just me, but I tend to remember the hours I put into a project on a particular date.
These could be matched to emails or requests and to proofs - I'm sure it can be pieced together