Looks like 2 weeks after Road America and 3 weeks before Laguna for the IMSA guys. Seems it gives those teams invited some more flexibility than before where the original June dates were a week after Detroit.
Sub to the race via the WEC web or App and watch it 100% add free. (Once the initial I can't get the stream to play bit is out of the way that is). It will then get put on YouTube. Use your downloader of choice and you've got a copy you can keep.