You are on the right track for sure. That wt. is good for a CAG. My Rosie being a timneh is just at 300 gms. Best to weigh before the morning meal and after the poop bomb then it will be accurate. I also remove all foods from the cage at night as my vet instructed. It works well. Here is one more educational link for you.
Winged Wisdom Magazine - Weigh Your Bird Regularly!! Pet Bird Care
Winged Wisdom Magazine - Weigh Your Bird Regularly!! Pet Bird Care