Hi and welcome to the forum! I am so sorry to hear of the loss of your Chloe. It does rip your heart out.
Getting your puppy will help your heart expand and ease your pain. You'll be amazed that there is a whole other area waiting to be filled by...Rex? If you don't like that name, I don't think it is too late to change it. I changed Mandie's when she was 4 1/2 months. Took about a week for her to realize I was talking to her when I said Mandie. lol...your pup will figure it out.
BB Puppy is a very good food. That is what I have given Mandie since the first week I've had her. She will gradually be changing to the small breed from the puppy as she turns 1 yr old tomorrow. I think sticking with what the pup knows and the fact that it is a good quality food is the way to go.
Can't wait to see pics and find out what you name him!