first batch of kombucha

So I follow the protocol for making kombucha using one GT drink and 3 liters of green tea. Two questions:
1. I used decaffeinated green tea. Is this ok?
2. Its been about a week and my scoby is about 2 inches long. I was under the impression it would span the entire length of the gallon container. Is that right, or does it start off very small. Tweet