Re: How long is too long, to wait for a model?
Longest wait I've seen is 3 years for a military model. To make matters worse, it was delivered with very bad QC issues. Was a retailer exclusive as I recall and said retailer spent most of a night sifting out the unacceptable models.
As for pre ordering, I think it depends on how popular the livery is. If another polished AA 727 was announced by Gemini, could be advisable to PO it. Sure, there's always a chance some might make it to retailer shelves... but would you risk not pre ordering if it's a model you really want.