I used PBS postage and mailed my book from home for the first time yesterday.  But when I click on the checkmark to go to the map to see where it's at, there is nothing there.  The truck isn't even on the map yet.  When I click details, it just shows the confirmation #, but nothing below it.  Is it normal for it to not get scanned when mailing from home?  I have always mailed from the post office.

Your book will likely be scanned at the first sorting center it reaches. That's normal. I mail from the package box at my PO (not at the counter) and most times I get an Acceptance scan but it's not uncommon for the books to go unscanned until they are En Route at a sorting center.

Yesterday was a Federal holiday, so it'll be a little slower than usual for scans.

For myself, if I mail from the blue boxes at the PO here in town, I generally get a scan 2 days later in Bell Gardens. If I mail from the blue boxes near my office in San Diego, I usually get an acceptance scan the same day and it's in Bell Gardens the next day. I think the bigger city processes more mail and moves it along faster, so if it's a weekday, I usually just take books to the office.

Recently I was mailing a stack of books with PBS postage.  I'd chosen "mail later" on most of them, but was actually mailing the day after they were requested, several days sooner than the mail date.  On the first few, I forgot to adjust the mailing date on the wrapper/label to my actual mail date, so the wrapper mail date was 3 or 4 days later than the day I dropped them in the mail box and marked them mailed.  On the others, I adjusted the wrapper print date. 

So my scans were normal on the ones where I'd adjusted the mail date.

On the ones where I hadn't adjusted it, no scans appeared until the mail date on the wrapper.  Once that date arrived, all my scans appeared, from the date I'd actually mailed the book.

...so that could happen too.

Local branches really vary in policy. Some scan, some will wait until it reaches the hub. There have been shifts in the USPS for the last several years, as they are changing the hubs and closing branches. It felt like some branches were scanning a lot, trying to prove how much traffic they had.

I mailed 4 books yesterday. I mail from my office, where they are picked up early afternoon, scanned when they arrive at the actual post office, then again at the sorting center. I find that the first scans are usually around 2:30 PM, and I get my quick credit later that night, between 8 and 10 PM. This is pretty normal and reliable in my perosnal experience. However, when I hadn't gotten quick credit for the 4 books I mailed yesterday despite watching the mailman take them, I tracked their DC numbers at USPS.com. Lo and behold, they were scanned once yesterday and once today, yet PBS is still showing no scans. So it looks like there's a delay in USPS sending info to PBS or the system itself isn't communicating at all. Not happy, as I was relying on those credits to place new orders.

I use PBS printable postage for my wrappers and get Instant Credit when marking books mailed so I don't typically watch the PO scans very closely. However, I do frequently check the progress of books I have mailed and it is not uncommon to see delays before routing information at various points along the route is updated in the transaction details. I have little doubt that this varies from one Post Office to another en route, but I also see inconsistent Delivery Confirmation Events from my own Post Office in addition to PO's en route.

Delivery Confirmation Events in my experience are irregular and spotty at times, but the books do eventually arrive at their destinations.

About two years ago the postal service decided that every package it receives with delivery confirmation will be scanned at the original post office.  That rule has changed a bit in some instances where there are a large number of packages, but a few packages brought at the same time should be scanned if you bring them to the counter.  If you put them in the blue boxes they might not get scanned at the original  post office.

It can take at least 24 hours for any information to show-up about the package.

Generally, it's best to just mail the package and forget it unless a couple of weeks go by and you don't have your credit.