People are wise to be wary of providing their information to an unknown entity. OTOH, I am persuaded that OP has developed software to perform check-in. A pure scammer wouldn't bother with Daylight Saving Time. What I see is one more case of "Wouldn't this be a cool thing to automate?" without wondering why it doesn't already exist. This is example of what you might call Chesterton's Non-Fence. If you come across a place where a fence should be but it's not there, ask yourself why it's not there before you build one.
When the auto check in phone number is entered into the Google Machine, it turns up on several blogs with the same tips and tricks. Appears to be a cut and paste complete with DST "advice".