I do the same thing, only difference is that I feed a size smaller than what they were originally feeding that way they aren't nervouse. Idk if that is necessary but it worked well for me, then five days later I fed what they were feeding them.

For instance:
Draco was in his tub for a week
I fed him a small adolescent mouse
five days later I fed him an adult mouse (what he was being fed before I bought him)
a day after his second feed I held him for fifteen minutes
five days after the adult mouse I switched him to one small rat (rats are generally preferred by most people on this forum for nutritional purposes).

You don't have to do it this way but it just makes me feel more comfortable and it was a flawless transition. I hope this helps! Congrats and have a great time with your new baby!