How to tame new dwarf hamster?

[Nelly4]

Hi all
Sorry this is a bit long :/
We got a new winter white dwarf hamster about 5 days ago. We got him from a breeder and with a pedigree so we know he is not a hybrid. He was born the 4th of july 2023.
We would really like to, in the future, handle him and hopefully make him a great pet.
My question is about how we approach this in the best possible way.

So, the breeder showed me how she handle him, and i am not sure i think that it was the right way. She would locate where he was sleeping in the cage, and then took both her hands around him and some of the bedding material and picked him up. So it was not on his terms, and while he was half asleep. She said i had to do it this way, so he would not get to bite or run away. You could see he was used to being handle, and when she put him in a smaller box/cage, he would clime up in her hands.
Now ive had a lot of hamsters, both Syrians and dwarfs througout my childhood and teenage years, and i would never pick up a sleeping hamster like this. She also told us that we should not give him treats with our fingers or in our hands, only when he was in our hands. Otherwise he would be disapointet when we did not have a treat or bite the hand because he would think is was food.

Now to my question: The reason i do not know how to approach this is that i have never had a Hamster that would hide when he sees us. The cage is located in a room next to our living room, to minimize the noise a little. We have a camera where we can see the cage, and he will come out of his hiding place a few times a day. As soon as we enter the room the cage is in, he will see us and hide.This also happens in the late evenings when he is awake. He will not come out when we scratch the bedding or talk in a low voise.
Yesterday i went to look in the cage, and could see him standig inside his house. This time he did not run away, i think the house was enough to keep him from doing that at this time. I put my hand in the cage, beside the house and he would stick his head out of the house to look. I put a treat in my hand, and he would come out, just by the door, and take the treat and then rush back. He did this two times, but not since.

I think it is really difficult getting him to get used too us, when we can't see him and he can't see us :/ Maybe he just need more time?
So, how do we approach this? Like the breeder said, because he is used to this? Or do we keep feeding him by hand? Or do we stop putting our hands in the cage?
Should we change the location of the cage, maybe to the living room where we are staying most of the day?
His cage at the breeder was much smaller than the cage he is in now, and maybe that is why he feels insecure?