Let me take a slightly different approach to your question.
It doesn't matter. It really doesn't.
What you should care about is when you RECEIVE your order. Leave it up to Amazon to decide when, and by what method, to ship it.
I order lots of stuff from Amazon. Most of it is with PRIME, but some items can't ship that way. Still, if Amazon says it'll arrive in 2 days, I don't care whether they strap the package to the back of a camel or put it in a jet. Same with things that don't ship PRIME and might take a few days longer.
Sometimes the package ships right away. Sometimes it comes by truck all the way from the origin. In other cases, it comes most of the way by plane. It really doesn't matter, and I don't care.
What I DO care about is that if Amazon says it'll arrive on, say, the 8th, that I get it by the 8th. And 99 times out of 100, I do.
Look: It'll ship. And it'll arrive on time. As for when it ships or its routing or the method used to get it to you, leave that to Amazon. OK?
Hope that helps.
Standard shipping takes around 5-7 days, plus there's no mail on sundays AND it's a bank holiday tomorrow.
it depends what time it was if its after 10pm pacific coast time
[since amazon is based in washington they use
pacific time,
for we know they haven't even process your order
then
yes they may say they have item stock
but its very possible the closest fulfilment center might
not have the all books you order
so then the order has been passed to another fulfillment center
Good grief give them a chance, they haven't started using drones yet .LOL. It usually takes a week.
If you really expected the order to be shipped before Monday you should have paid for the fast shipping. There is no shipping on the weekend from retailers.