start in the 1st room lost, start low, they dont climb much. Few tricks is one the flour trick like you said put a straight line of flour at each doorway. Will help you when your not home or at night you can tell which way the snake went. Ive also heard of putting plastic shopping bags near corners and places you think the snake may go by and keep your ears open. I think the plastic bag trick was more for escaped rodents but I dont think it can hurt.

He's not going to wonder much from what Ive experienced. They usually will find a comfortable place and stay there. I found a lost snake in a cabinet which was gone for a month. I gave up looking after a week or so, The snake must have been in there for at least 2 weeks or the whole time, there was shedding and 2 separate poops, which made me know he was there for awhile. lol Double look things, there good hiders

GOOD LUCK