Hi Jim,
May be there are many possible ways to follow to get the information you want. But, I suggest you to use a search step for searching a server's (or any other object's) processing queue to get such information. You can search not only the server's processing queue but also the whole "entity population" to get whole state variable's defined on them at any arbitrary time thoughout the simulation run. All you have to do is to define additional expressions on search step. In the example file attached a simple model is developed to get entities' state variables residing at server1's processing queue. Here note that, you have to click button at arbitrary times. Then, if 3 or more entities exist at server1.processing queue, the search step founds the first 3 of them (since a forward search is performedin this sample model) then later an excel write step writes entities created time (you can get many state variables of entities written on the same excel file). You can change search limit, queue state name, include a match condition etc. If you want to get such information at the beginning or at the end of the simulation run you should use this same logic at appropriate processes (onrunending, onruninitialized etc...). Also, you can get these information written on either a database or an output table as well. Hope this helps?
getting a snaphot of Entity WIP via a button.spfx entities_processing.xlsx