We started crate training Kirby from day one. He was so small that I used this carrier. I would place him in almost every time he was getting sleepy so he could get used to it. He would go to the back and snuggle up to hs teddy bear for a nap. The second I heard him cry I would let him out. When I went to bed I placed the carrier on one of my nightstands so I could talk to him whenever he whimpered throughout the night. This carrier became one of his preferred safe places as he would go into it on his own whenever he wanted.