Advice/Help for Private Hybrid School Library

I posted this in the Catalog Flash-Mob, but I realize it's a dormant group, but I'm desperate. I taught at a small Homeschool Hybrid Classical model school in South Carolina. My director has a massive collection of books and school materials that were in her garage. All those materials are now in a storage unit, and I'm working on cataloging them and creating a usable library, but I am desperately in over my head. I have a MLIS, so I volunteered. but I'm rusty and slow in cataloging (never got a full time library job). I need to finish the library by August, but I'm drowning. I've added nearly 1000 books, and there are still a ton to go. My catalog is currently a bit of a mess because I was trying to teach four classes, work on my dissertation, and do library stuff, and that did not go well, but it's summer and I have fewer demands on my attention so I can clean things up. I would appreciate any advice anyone can offer or if you're in South Carolina...

Do most of the books have bar codes? You can get a quick entry by using the LibraryThing app to scan the bar code and enter in an instant. The data may not be perfect, but you can clean it up later, and it would be a starting point.

>2 reconditereader:
Yes, most of the books have barcodes, and I scan them with my phone; however, many homeschool curriculum publishers don't have barcodes (I'm looking at you, ABeka(ಠ_ಠ)). I have a whole library cart of books that won't scan.

My current process:
Scan books into LT
Download into Excel
Assign Call Numbers (I've been using Dewey, but I'm not opposed to changing)
Assign Tags

For a while, we didn't have a printer at the school (don't ask 🙄), and I could not create labels, so I focused on cataloging/call numbers for as many books as possible. I'm still working on a 300-item-long list of books to assign Call Numbers, and I scanned in more last week.

Perhaps my process is bad.
Or I need to switch to LOC subject headings/call numbers.

I'm open to any and all suggestions.

When I offered my library skills, I was unaware of how much material my director had stored in her garage, but she's been homeschooling for over 20 years and loves (loves) books.

I would, if I were doing it, not assign tags until I had all the books listed in the catalog. Don't aim for the completely, perfectly professional set up until you have a basic catalog. A keyword search on titles would make it possible for a library patron to find enough books on a topic to get started, I think. Assigning tags or subject headings is what slows me down.

If you are picky with the source (try clicking on the grey square icon with the question mark inside it to the right of any search result) the DDC number should be filled in for you already, so you don't have to assign anything manually (except in cases where you find books no source has added yet — I feel that pain, especially with educational resources). You can add tags as you go with the quick edit feature, but without knowing more about how you are using tags specifically I'm afraid I can't be much help with that.

Personally, I would not export to excel or anything that requires exporting to excel until you are done with the entire library (or, if you have to be on location to add books, I might do whatever part of your workflow is on excel on Saturdays, or one day a week when you're at home).