Straps at/above shoulders- when in doubt?

[Snow mom]

DD is 3.5 and rides FF in a classic marathon. She's not very tall for her age (38") but I'm having a hard time determining if her shoulders are sprouting up past the third slots. Sometimes it seems like they are below, other times above (I'm sure depending on how she is sitting.) So if in doubt, should I move up to the top slots? They seem really high but I guess crash dynamics says 2 inches above the shoulders is better than 1/4" below the shoulders when FF?

Anyone remember at what age they moved to the top slots in a classic marathon? I guess I thought she would be older when moving to the top slots.

[Simon]

One technique is to line up the cover and shell then slide a butter knife (letter opener, other stiff object) and see how it fits relative to her shoulder. Does her shoulder lift the knife or does it dip down to rest on her shoulder? That has been our fail safe for testing when we should move the straps. But, yes, afaik, up above it better then below for FF, even if moving up places them way above.

[legaleagle]

I would probably move them up too. She may "grow" slightly too when the straps are definitely not pushing down on her shoulders.

[Snow mom]

Thanks for the butter knife suggestions. I've always used my finger and it certainly isn't the best implement for determining strap height. I do think she's a smidge above the third slots and I have moved the straps up to the top. I can't believe she's already on the top slots. I'm sure it will take close to forever to grow from the bottom to the top of the last set of slots but I still can't believe she's gotten so big.

[AJP]

I just moved ours up to the top slot too. My girls were a hair over using the knife method. Can't believe they're getting so big!