The old layaway plans are the opposite of financial sense when it comes to material goods. They lose value far more than you’d pay later.
Yes, usury credit rates aren’t much better, but delaying the ownership breaks the fundamental principle of time money value.
So I would lay the product away, cash my paycheck a week or so later and bring cash to pay off the item.
Why would I bother doing this instead of just waiting to have the cash in hand? Well if the item was on sale, you would lock in the sale price if you didn't have the cash today. Also, if the item was out of stock later, it might be weeks or never before that particular item was restocked.