If you want to ride it twice, then yes, do FOP at RD first. If you find your position is not that great at RD for the FOP Standby line, then just jump out and go to a plan B and do something else and do your FOP later with FP.
Are you at the end of the line at Tiffin's? If so, that seems very far back to me, but I don't know how they snake the line at park opening. My guess is a CM will be around with a sign to indicate the end of the line and he or she should be able to give you an estimated wait time. I do think FOP is worth riding twice, but not sure I'd wait more than 30-40 minutes in line when I had a FP later on. I think your wait would be at least that.
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