It says 5 days here: http://www.expansys.com/samsung-i910...i-16gb-209114/
I also got an email from expansys today that said they are shipping out the phones on tuesday (which incidentally is 5 days from now).
It does say 10 days in the order tracking tool for my order though, but that is because it's got the wrong product code in the order tracking (asked them about this in an e-mail a couple of days back).
May 2nd is also a bank holiday in the UK so that's probably why they are sending them out on the 3rd.
This is the e-mail I got:
Originally Posted by Expansys
We are glad to announce that the first delivery of Samsung Galaxy S
II devices will be done next Tuesday.
Please have in mind that despite what has been first communicated,
Samsung informs that the Galaxy S II does NOT feature an NFC chip.
If further to this new information you wish to cancel or freeze your
order please contact us.
When I look at the wording they might even mean that the first phones will be delievered on tuesday and not sent, guess we'll see by tuesday.