A little unfair on the club to say it's a commercial shambles.
It's quite feasible that different sponsors were waiting to see which league Oxford United would be playing before comitting themselves, or negotiating the size of their offer.
Remember, its not just the main shirt sponsors, back-of-shirt and short sponsorship also needed sorting. There were a lot of ifs-n-buts until the Wembley match.
Once League 1 was confirmed, talks with sposnsors would have needed to be finalised, counter offers made, or even new sponsors found.
So assuming the sponsors are finalised, artwork will need to be sent to (Puma's?) factory and production time alotted. Once produced, the garments then need to be shipped to the UK.
All of the above in the space of three weeks? Hardly P**s poor!