He's very cute indeed. I wouldn't worry about him being only 8 w/o, I've had Blossom since she was 3 weeks. And previous cats 6 - 7.5 weeks old, things were different many years ago.
I really wish I'd have thought to start putting a harness on my cats when they were tiny. That way they'd be use to it by now. But there's NO WAY they'd tolerate it now.