adopted 2 kittens 2 1/2 days ago one has purred and the other hasn’t

as the title says i adopted 2 kittens (3 months old) one of them has purred and is such a sweet girl. the other she hasn’t purred yet. she seems skittish. i’m worried she won’t purr. i just hope she’s happy. she has cuddled, she is letting us pet her and play with her. she’s also been licking us. but no purring.