Haven't stayed at that hotel but stayed at one nearby, the hotel shuttles run fairly frequently and I would imagine they'll be regularly running by that time. It'll depend how much luggage you have for how long it'll take to get your way to TGV station. Just make sure you have all your stuff down with you for breakfast so don't miss a shuttle by having to go back to your room.
If you're flying into CDG the night before make sure you check route from shuttle bus dropoff to TGV station. The first time we flew into CDG the only thing slowing us down was not knowing exactly where everything was. Also I would imagine you could collect your tickets from machines the night before too which would save time in the morning.
I'm assuming you're after the extra hours by early start but is there much of a difference to the next TGV? I think your plan is doable but it'll probably make it a hectic start to the day.