To be on the safe side you should get it in the fridge as soon as it is cool enough to do so.
The main danger is botulinum toxin produced as you say by bacteria. I have a feeling though that if you cook the curries like a restaurant, i.e. full heat from start to finish, the botulinum will be broken down into 'safer' compounds. It might make you ill but it probably won't kill you!
What you really want to watch for is avoiding, as much as is possible, getting the actual base scooped in with the oil as this is yummy stuff for all sorts of bacteria to go to work on. If you scoop before you blend your base this should not be a problem.
If you are ultra worried about this then you should really pass the oil through muslin or something similar before refrigerating.
Needless to say, if I know that I'm the only one that's going to be eating my curries, I studiously ignore all the former advice.?
