how fast should she grow ?

my bp is about 18 inches i have had her for about a week and she eats full grown mice. thats what the guy at the pet store was feeding her i was ready to give her a fuzzy when he asked me if i was feeding the snake i just got from him then he toled me she eats larger mice. sure enough when i fed her she took it down no problem. but what im wondering is how fast dose she grow. i would think when shes young that she might grow fast and when she gets older she might slow down some. in the next year what should i expect ?

usally on average about 1ft a year for the first 3 years