When will AMEX report new credit line?

My AMEX account dates back to 2003. However, I applied and received 2 new cards (Platinum& SPG) in the first week of October. Both cards were back dated to 2003. When will they be reported to the credit bureaus? If I report a small balance, will that effect when they report? Also, what impact will adding these cards have on my score? Will the impact be offset by the inquiries?

Thanks for any input.