I have never tried this so I don't know whether it will work but this is how I would do it.
1. rinse the sand thoroughly so that you get rid of any very fine particles - these will make the water cloudy almost instantly, though can be removed with a fine filter medium.
2. soak the sand in established tank water
3. I'm not sure how big your tank is so I don't know how much sand you intend to put in there. You may need to do this several times. Put the sand in a freezer bag and try and get rid of as much air as possible when you tie it off.
4. Hopefully the bag will now sink to the bottom of your tank. Either untie or cut the bag open and gently tip the sand out. Be careful as any movement will create a current and will disturb the sand.
Whatever you do you will probably find that some of the sand gets disturbed and any fine particles will cloud your water until your filter removes them. But this is the method that I would use but as I've said I've not tested this method.
An important point to note. I would leave your filter off for half an hour to let the sand settle. I am of course assuming that you don't have an
ugf as I believe these are complicated when using sand as the substrate.
Good luck and if you use it let me know how it goes. You may find that someone else has a tried and tested method however.
Liz
Planted 50g community tank.