Penmanship Practice

How strict are you when it comes to sitting properly for penmanship practice? Princess Boogie, 4, is just learning how to write, so I haven’t been a stickler about having to be 100% about her posture (In fact, I’m not sure I was strict about it with College Boy, 19, either). Right now, it’s student-initiated. She wants to learn to write, but she’s also a wiggle worm. (The book is Zaner-Bloser Handwriting Level K – I’ll write more of a review of their products soon). So: Sit down feet firmly on the floor or kneel at the coffee table/wherever else she happens to be when working on her letters?