Hi and welcome,
It's a bit tricky to answer this exactly for you as "Acceptance Time" is something which has been designed specifically for you and it may possibly be that it hasn't been designed to store the time in a way that you can easily query on (it may just be held in the audit trail of an incident). Do you have an action that you click when you have accepted an incident? If so then perhaps there will be a collection object on you attribute list which will hold this value when expanded. When modifying a query via Query and Report Designer, you can tell which are collection objects as they have a symbol to the left of them which is 3 joined boxes (indicating one to many table relationships).
Rather than me trying to guess, it may be better if you are able to ask your support provider to assist you with this query modification. If you have direct Support with LANDesk you can do this via the link below but you need to have your community login registered with your company email account in order to gain access:
For some more general guidance on query design there is the Designer manual:
There's also a document that I wrote some time ago with some additional tips on how to find the right information for your queries, that you may find useful: