For Kindle you upload the PRC file created by MobiPocket. Amazon tells you it will take about 24 hours for your book to be checked. It goes into "In Review" status and you can't do anything in that time. Then it goes to "Publishing" - during this stage it will appear on various Amazon sites (exciting, eh?) but won't be available to buy. Again, Amazon says this takes 24 hours - for me, the book appeared on .com and .co.uk much quicker than that, and was available to buy long before the status finally changed to "Published".
For CreateSpace, you upload your files then it tells you to wait for what could be a few days while it checks and process the files. For me, it took about 3 hours before I received confirmation that it was OK. I then made a change to the cover file and uploaded again so had to wait for another few hours.
Once approved you then have to order a proof - you can't make the book available for publication until you order the proof. Again, CreateSpace say this might take some time, and estimated delivery might take up to 6 weeks to get to the UK. I was surprised, therefore, to be told the proof had been dispatched less than 12 hours later. Of course, I've not received it yet.
You have to approve the proof before you can continue. You could approve it before you receive it, but that would be foolish, so it's now a waiting game...
When you upload the file to SmashWords, it does some checking then converts to the various formats. You can sit and watch that happen (I did!) - it takes about 10 minutes or so and then you can download all the formats for checking. I found that the ePub version had lost many of the formatting changes I'd made. It's not a disaster, but not as good as I'd like. As yet, I don't know if I can correct that. The other formats, though, appear to be OK.
So, your various formats are now complete and available, that's the hard work over, right?
Oh no. The hard work hasn't even started yet... and I'll get on to that tomorrow.