First time cleaning enclosure how?

[Bogertophis]

I have just looked at him and he is about to go into shed. His eyes are a little blue already.
So feeding falls flat than?

I would skip feeding. He'll probably refuse & you'll just waste the food. No point- he's fine. Snakes evolved to skip meals- they don't live on "schedules".

But since he's not eating, you could go ahead & clean his enclosure now.