There's no real measure for Stardates, any calculator you would find online is not official. The writers themselves have said they didn't have any real system for stardates, they would just make them up.
The only accurate suggestion for when the book takes place is sometime between Drive and Lineage. A safe assumption would be closer to Lineage based on a comment Tom made about no longer being considered newlyweds.
Why not read the book...it's VERY good.
I don't care if it's official or not. The calculator I use is from the 90's and is rather accurate when it comes to placing Stardates into one Earth year. For example 1 January 2371 12.00 will be Stardate 48001.36 and 31 December 2371 12.00 will be Stardate 48998.63.
The Stardate for "Caretaker" is 48315.6=Monday 26 April 2371.
I'm sure that the producers did take those Stardates into some consideration because they seem to fit perfectly into one year. The stardates for year 2371 starts with 48, the stardates for 2372 starts with 49 and so on.
As for Jeff Ayers's suggestions for where the novels fit into the timeline, most of it is pretty acurate and realistic, however there have been some questionable suggestions as well and it looks like his suggestion for "The Nanotech Wars".
In fact, Ayer's suggestion for the book "Chrysalis" between the episodes "Lifesigns" and "Investigations" was also wrong because there was a mentioning of a newborn baby in the book (Naomi Wildman) so the episode must take place after "Deadlock". I took the liberty to place the events between "Resolutions" and "Basics#1".
In "Voyages Of Imagination" the main events in the book "Mosaic" is placed between "Tattoo" and "Cold Fire". But the events in the book must take place after "Meld" because Tuvok's mind-meld with Suder is discussed by Kes and The Doctor in the first chapter of the book. The Trabe also appears in the book and Voyager had already had first contact with the Trabe in the episode "Alliances". So placing the events in the book between "Meld" and "Drednaught" would be more realistic.
But such errors makes the timeline-creation more exciting and interesting, don't you think?
I'm slowly starting looking at the Star Charts and Stardates for seasons 4-7 as well in order to continue with the timeline for seasons 1-3 which I've come up with so far.
As for reading "The Nanotech Wars", well maybe someday.