How far ahead of time are they usually made available? I've never planned a trip to DLR this far in advance before (4-5 months) and am not sure when to expect them.
Disney doesn't make the official rehab schedule official until maybe 6 weeks to 2 months (!) out.
Other sites sometimes list rumored rehabs farther out than this, though. The Dis has a list at http://www.wdwinfo.com/disneyland/plan.htm#rehab and other sites like MousePlanet list rehabs as well. (In the case of MousePlanet it's at the end of their weekly updates.)
unfortunately disneyland usually post the official rehab schedule about 6 to 8 weeks out.
If your going in july or august you should be fine, there most likely wont be any rehabs.
in september haunted mansion and space mountain will be closed for a few weeks to install the halloween overlays
The Dis has a list at http://www.wdwinfo.com/disneyland/plan.htm#rehab and other sites like MousePlanet list rehabs as well. (In the case of MousePlanet it's at the end of their weekly updates.)