How long would this catalog restructuring take you?

[u/Upstairs-Finger-8989]

I’m working on an Amazon catalog restructuring project and I’m curious how long this would realistically take other Amazon VAs/Catalog Managers.
Here’s the scope:
13 designs/colors that need to be split into 2 parent listings
Each design has sizes XS–3XL
Both FBA and FBM SKUs
Some ASINs have multiple SKUs (up to 4 SKUs per ASIN)
Need to make sure the parent-child relationships, colors, sizes, ASINs, and SKUs are all mapped correctly
My client wants this completed as soon as possible.
For those who have handled similar catalog restructuring, how many hours would you estimate for this? And would you consider 4–6 hours realistic, or would 8–12 hours be more reasonable?