He is a very handsome fellow.
I can't tell how exactly how old he is from the pictures but the stripes on his head indicate he's already been through his first full molt which would generally take place at around 3 - 4 months.
Have his his iris ring developed fully at this point in time?
I would say your estimation of about 6 months old is fairly accurate.
We think he is about 15 weeks old? Hard to tell his eyes to me look dark. This Baby is the friendliest Budgie I have ever seen! He sings, talks steps up and loves being out. We adopted him from someone that needed to re-home him.
Here are a couple of pictures that hopefully will help determine his age.
Scooby is a great name and he is just as cute as can be.
I'm sure he's going to need his own on-going picture thread made in the Budgie's Pictures section of the forum so we can see lots of him as time goes by!