Timothy hay as bedding?...?

I have a 4 week old degu that I've been hand raising...I have him in a small hamster cage at the moment..and I have had a heating pad wrapped in a towel on the bottom of his cage turned on 24/7 to keep him warm. But I read that when they start to weigh around 25g..then theyre able to start controlling their own body heat...sooo I was thinking of taking out the heating pad soon seeing as he's around 30-32g now....I have timothy hay i bought him to munch on...but I was wondering if it was fine for me to put as bedding? it'd be cleaned quite often...I just wanted to know if anyone else uses timothy hay as bedding and if that's normal? thanks in advance!