FWIW... The decision is pretty instant. It might pend for two or three days, but no longer than that. If you weren't given an instant decision then it is probably because some piece of information you provided on the application wasn't verifiable through the directories. If you put a PO BOX or an address that doesn't show on your credit reports, for example. Anyway, call them in two days and they can give you the status of the application. If your credit is below 700 then I wouldn't expect a high line of credit if you are approved. Even with a 700 I have seen a lot (and I do mean a lot) of declines because of other credit factors. Your report has to be squeaky clean these days. It may have been 10 years since your bankruptcy, but be sure that it has been removed from all three bureau reports. Also, if American Express was included in the bankruptcy then you can pretty much forget about ever getting a card with them until they get their money back. Just because it isn't on the credit report doesn't mean a business can't remember being screwed.
Just as a tip, the standard Green American Express card is probably one of the easiest to qualify for. It has a lot of benefits going for it as long as you are willing to pay it off in full every month. With any problems on your credit report you can expect to see maybe a $1000 credit line on any other card product, so if you don't want to cap your monthly spending then the green is probably the card you'll want to try for next if the Blue Cash doesn't work out. Good luck!