As I mentioned in the other thread, I think you may have gotten lucky. Which is great, and it does prove the old HUACA method can be a real winner. Always worth a try!!
If anyone else tries this method and succeeds it would be really interesting to hear.
As an aside I personally don't think it makes any difference if you tick the AMEX member on the application or not. AMEX is already doing the data matching and knows you are an existing card holder - they even print it on the card.
I've noticed a few people are having to wait many weeks for there bonus points recently. Like 4+ kind of weeks. This doesn't seem to be the majority of people, but differs from previously when it seemed to be almost instant for everyone 'eligible'.
So whilst I wouldn't hold out too much hope, I also wouldn't rule it out. Fingers crossed for you!