The spr to helium snapshot will occur on August 1st with the coin going live as of right now set to September 1st. They are working with Bittrex to see if they will facilitate the exchange but that is still currently up in the air, otherwise and escrow service will be used. The ability to transfer spr to helium will run for 1 year but as I understand it the spr must be bought before August 1st. It's an exciting sounding project with some level headed talented dev's. Running a master node is set at 1000 helium so I'd recommend getting in now if you plan on it.