Hi
The shifting of receipts is shifting back from the issue limit end. i.e. in this case shift 08:00 hours back from 24:00 = 16:00. Hence in CO09 screen or in Product view in APO you will find these date/time when your order is confirmed. This is very easy to model in your sandbox system, please do that to get better clarity. Please refer to my blog for details on this: ATP Bucket Strategy
No it is wrong. Availability Date does not change with time you create the order when your bucket logic is Conservative Logic. Hence it will be 16:00 for all your orders irrespective of when you create. The confirmation date might differ though.
Hope this was helpful.
Best Regards
Parth Soneji