My bag is iris.
Congrats! What a lovely color Iris is. Generally speaking Togo leather should not require any weather proofing; simply pat you bag dry with a soft white towel if it gets wet. As to keeping your bag looking new for the longest time possible.. here are some tips
1) When not in use store your bag straped closed and laying on it's back in it's dust bag.
2) if you live in a damp climate it's important to not leave the plastic on the hardware as mositure can seep under and lead to pitting of the metal.
3) do not expose your bag to long periods of direct sunlight.
4) do not spray your bag down with any silicone or acrylic protective sprays these are not good for the leather...
I hope this helps?