Baby Jenday Conure Biting

I got my Jenday Conure sometime in September of 2012. He was born in April, so he's only a few months old. When I first brought him home, he was very good and I could hold him a lot. But recently he's been very nippy.

I asumed he was in a stage where young birds have beak exploration as he tends to bite anything around him (ex. my hair, toys, clothes, my laptop keys, etc.). I've tried telling him "No" in a firm tone and putting him in time out, but he would go back into the same behavior.

If I hold him and he does not bite (which is very rare), I will reward him with a treat. Hr also does this thing where he forces his body weight over my finger so that he swings upside down while chewing my finger. Again, it seems to be playful. It doesn't always hurt, though sometimes he can bite harder.

He's my first bird I've been able to hold, so I'm really not sure what he's doing or how to address it. If anyone knows what to do, I would greatly appreciate some advice :) Thank you!