Is this behavior normal/healthy in a snake? (New snake owner)

[Saika]

Thank you so much for your advice guys!!! I really appreciate it! I fed him and he ate like a champ and even went to ask for more. But now I have a new problem.... I don't know what I'm doing wrong. He's very skittish which is to be expected but he runs from me at the sight. If I open the terrarium, he seems to borderline panic (unless there's food). I thought maybe I could play with the substrate and get him used to my scent a little. He stayed still but then I lightly touched him and he rattled his tail and quickly tried running to the other side of the tank. I feel awful that I stressed him out. This was approximately 35 hours after he ate. I only touched him. Seeing him panic like that and rubbing his nose against the glass to get away makes me kind of scared for when I have to handle him. And he's really fast too! How do I do this? Should I not touch him like that? What did I do wrong? How can I handle him in the future and actually pick him up if he's speeding away with just a touch? I'm sorry guys...

I change his water daily. Will it stress him out for me to do that or should I wait 2 days?