The only thing you'll save is time if you just order the sub mini connector now instead of looking for an adapter that doesn't exist.
I switched from Nikon and bought an R5 & R6 at about the same time. I could not believe the amount of incompatibility between the two from an accessory perspective (at least the grip was). I ask my pro rep friend why they'd do such a thing and he just rolled his eyes, completely unable to explain the logic (or lack thereof). I ran into this with Nikon as well, so I never buy hardwired accessories any more - everything has interchangeable cables. This worked great because all my 3rd party "Nikon" stuff works with Canon if I just use the right cable.
