Hi Chelsey,
I don't have much knowledge with Google Shopping sorry but I thought I'd just suggest when you come to the time of creating unique product descriptions, headings and title tags this can be automated. When I have websites like this I create rules and formulas and pass to the developers to implement.
Example: Title tag: [product name - or pull from
header] [product code] - [category] - [branding]
Meta description: use the first 165 characters from the product description
Body copy: Swap out the [product code], [product color etc], [category name] but use a similar description as the base. It would be great if we could write individual descriptions for product pages but if you have a site with thousands and thousands of pages this isn't a reality.
header: Will need to be added by hand via a CMS but you can make these unique by adding the product code (or colour or size etc) at the end.
Also another thought, why don't you only add noindex to the product pages only on go live so at least your homepage and other content pages have some time to get indexed before the product pages are ready? Alternatively you could use a robots.txt file to block the folder directories of product pages while still allowing search engines to index those important high level pages (instead of noindex).
I think it's great you are taking the time to provide unique product descriptions!
Good luck,
Davinia