If I understand your brief explanation, @jacekm, you are correct. For billable time, the account Billable time - movement is work in progress. (In fact, for my own business, I have renamed it that way.) It recognizes the revenue at the moment the time is entered. The value of the work in progress gets transferred to another income account when you invoice. I got the impression, however, from your first post that you wanted to be able to track work in progress other than just billable time.
This subject has been discussed on the forum quite a bit. See, for example: Pre-invoice - #2 by Tut.
A search on “work in progress” turns up many topics.