I'm sure they will do whatever they can to accommodate as many people as possible, but there is no way they'd be able to move everyone with tickets for the first preview to the evening that seemingly, will become the first preview. If they can't find a date that works for you, they will refund your money. (Make sure you fight to have any fees reimbursed, too.)
With early previews, you always run a risk that they will have to cancel....sometimes the actors aren't ready, or the set, or a million other things. (Doesn't make it stink any less.)
If we're not having fun, then why are we doing it?
These are DISCUSSION boards, not mutual admiration boards. Discussion only occurs when we are willing to hear what others are thinking, regardless of whether it is alignment to our own thoughts.