Just a small point though. I wouldn't rush the change over because with baby hamsters you need to take care that they feel secure and settle while you tame them. This is much easier done from a smaller cage like you have. Remove the tubes and start careful taming. One you get the new set up he should firstly have playtime for short spells in it and then back to the smaller cage to sleep. You can move some of the familiar items when he moves over completely. Try and not fret over the cage size for now. He is a baby hamster and needs calmness and routine before a move to a large cage which can be stressful and overwhelming for a baby
