I never really put top knots on my Heidi..i did once...but she obviously didn't like it and rolled and rolled and rolled until she had a big mess on top of her head!!
so i never tried again...I should think it's something you should start from as young as possible...as soon as the hair is long enough to tie up?
I think thats the mistake i made with Heidi..i didn't start doing it when she was very young but i always kept her hair very short anyway.
With my new girl (when i do finally find her!) i will start as soon as possible!
I think it's the same with clothes..i plan to start putting little T-shirts and jumpers on as soon as i bring the new baby home but i would never force her to wear something if she really wasn't happy with it.