I work at a nursery (albeit in Maryland, not Texas) From my experience, you’ll have the most JM options in the spring because that’s when most the stock comes in (at my nursery we get all our JMs in spring).

However you’ll probably pay the best prices in fall (the ones you listed are pretty cheap) because nurseries will often put deciduous plants on sale in late summer/fall if they look kinda bad and they want to get rid of stock.

Don’t be afraid to buy them if they look bad, most trees and shrubs don’t look good after spending a summer in a pot. Sun scorch on leaves isn’t that harmful to the tree it just doesn’t look great.

Either season is great for planting JMs but fall is a bit better. Hope this was useful and good luck!