I did a bunch of conversion testing last year on my businessy blogs (that gets over 10k uniques a day) and I've found the following:
-Best posting time for max exposure: Friday, 4pm
-Best for retweet exposure: Saturday, 9am
-Best for facebook share exposure: Sat/Sun, 8-9am
Things to keep in mind is that the demographic might be different in the arts and crafts crowd than the business crowd and the data is old, so it could have shifted somewhere.
But it does make sense to me that it looks like the way it does. So generally, I like to post in the morning-ish, like 10am-Noon (after taking into account the time zone difference, I am on the east coast) since people at work, in front of computers tend to share around that time. If i really want to expose a certain post, then I shoot for a late friday post. Its worked fine for me so far.
I also second what Heaven says.. its better to be consistent than sporadic. I personally like to schedule my posts for the next day "prime time". I don't usually publish right away unless its a time sensitive post or if I forgot to publish it and saved it as draft instead (like I did today *sigh*)
Also, for enabling your blog on kindle, see:
https://kindlepublishing.amazon.com/gp/vendor/sign-in?ie=UTF8&originatingURI=%2Fgp%2Fvendor%2Fmember... (not sure what's up with the images?)