If you want to assign a specific notary to an order, just create your new order and click 'Search Agents'. From there, find the notary you want to assign in the search results, without starting the automator. If the notary is already favorited in your account, you will see them at the top of the search results.
When you find the notary, click the blue 'Assign' button next to their name. Once they accept the signing, they are automatically assigned to the order.