so i am curious which rtv you use on the water pump, and how long do you wait for the rtv to dry before running the car? i have been using blue on the water pump and waiting the full 24 hours before getting the car going again.

 

I've always used Ultra Black on anything engine related. Any one of them will do. Just don't use Ultra Grey by any means or you'll be trying to pry the wp off w/ a crowbar come time to replace it or just take it off, not to mention the amount of hours scraping that **** off the block.
Are you using gaskets? If so, then it's really not necessary to use RTV. But if you want to and because you aren't sealing some large gap like an intake then you can run the engine as soon as you're done.

 

I use blue if I use anything on the water pump, but you can install it dry as well if you're using gaskets as already mentioned.

 

If you use a very thin film on the gaskets, it won't be hard to remove the next time. I don't worry about drying time on those gaskets.

 

On water pump gaskets, I usually use a spray dressing like coppercoat.

 

That's true. The one thing I didn't think about is how challenging it can be to remove the gaskets once they've baked onto the block.