I’m so sorry! I hadn’t checked my inbox for a while obviously. Here’s that pattern if you’re still interested.

https://www.decocuir.com/blogs/blog-tutoriel-patron-cuir/tutoriel-sac-cabas-cuir-couture

I dunno about time wise but I only made 2 wallets and 2 basic tote bags before I tried this. Granted there was a bit of trial and error involved where I’d make a mistake and have to recut a piece etc on those first bags. Good learning experience though! I don’t think you need a ton of practice to make something like this. Just take it slow and make sure you have all the pieces cut out properly before you start sewing. This was made from a free pattern I found online if you’d like the link.