Originally Posted by GUWonder
Is there a cut-off deadline (e.g., six months after stay, one year after stay, etc.) for requesting retroactive credit?
Waiting 90-120 days for them to post. I guess in some ways that's better than having them never post and having to follow up on the matter.

My experience is quite simple and positive:
something like 95% of Hilton generated miles posted on time. Tumb rule is that the miles for month N (e.g. June 06) will appear on the 10th something of month N+1 (e.g July 06).
When something is not posted, verify if any later stay was successfully posted and if so, write a nice e-mail to the HH customer service, they will take care of manually send the involved miles on the next run, the following month. Due to a monthly schedule and try and error verification can take a lot...but read it right, with over 100 involved stays it happened only twice to me and it was eventually fixed.
Once with a different hotel chain and different airline FFP it took 2 years for 500 miles. I was quite surprised when they finally appeared.