Cooling fall weather and, hopefully, additional moisture make for ideal conditions for planting hardy perennials. Fall planting allows for two growing seasons, fall and spring, before their first hot, dry summer. 

There will be two rounds of September sales and one round in early October. I do recommend that a good layer of leaves or wood chips be spread over October planted seedlings as the ground freezes though, to prevent frost heave of the seedlings.

I run the sales on two-week cycles. Every second Tuesday I will update the inventory with the species that are ready to go and open the store for orders that evening.
You can place an order and select from a few pickup days and times (a blend of daytime and evening options) from late that week and through the following week.
I close the store to orders the day before the last pickup option on the second week (so usually Wednesday or Thursday) and then consolidate the partially emptied trays, move any seedlings that are getting crowded up to larger size trays and transplant more young seedlings into plug trays. Once that is done, I update the inventory with whatever plants are still available, or that have matured enough over the last two weeks to be ready to go before and start the cycle again.
While not every species is available all season, I try to keep a pretty wide selection available from mid May to mid October, with between 100 and 200 species on offer at any given time. 
Each individual round of sales is first-come first-served for the available plants but there are usually more coming along since I start some early and leave others to germinate outdoors.

In addition to the store page updates, I've added pages about restoration plantings, including a list of species growing from locally gathered seeds, and a page on community and school plantings.