Please don't take this the wrong way, but just as an FYI it's best not to discuss smaller systems on an open forum like this. Now I haven't been to the Chehalis this year at all, but I'd rather find out for myself than have someone post on here about this system. In years past, whenever someone posted about the Chehalis, it turned into a complete gong show. It still may. Anyway, it's always best to go for a hike and look for yourself. It's not always about catching fish. Pre-scouting can pay off dividends for the upcoming Fall run.
As for timing, it is getting quite late for the summer chinook on our local systems. You can always catch fish, but you will be likely weeding through lots of dark fish if you find them.
Just my 50 cents worth. Otherwise, post away at your (and other's) peril!!!